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Oracle uses National Language Support SORT. This gives the collating sequence value of the given string based on the collating sequence sort , or if omitted, the National Language Support option chosen for the site. REPLACE( string , if [, then ]) REPLACE returns string with every occurrence of if replaced with then (zero or more characters). If no then string is specified, then all occurrences of if are removed. See TRANSLATE. RPAD( string , length [ ,' set' ]) RPAD stands for Right PAD. It makes a string a specific length by adding a specified set of characters to the right. RTRIM( string [,' set' ]) RTRIM stands for Right TRIM. It trims all the occurrences of any one of a set of characters off of the right side of a string. SOUNDEX( string ) SOUNDEX converts a string to a code value. Names with similar sounds tend to have the same code value. You can use SOUNDEX to compare names that might have small spelling differences but are still the same. SUBSTR( string , start [, count ]) SUBSTRing clips out a piece of a string beginning at start position and counting for count characters from start. TRANSLATE( string , if , then ) This TRANSLATEs a string, character by character, based on a positional matching of characters in the if string with characters in the then string. See REPLACE. TRIM ( [{ { LEADING | TRAILING | BOTH } [ trim_character ]) | trim_character } FROM ] trim_source ) TRIM removes all the occurrences of any one of a set of characters off of the right side, left side, or both sides of a string. UPPER( string ) UPPER converts every letter in a string into uppercase. USERENV( option ) USERENV returns information about the USER ENVironment, usually for an audit trail. Options include 'ENTRYID', 'SESSIONID', and 'TERMINAL'. USERENV is still supported but has been replaced by SYS_CONTEXT's UserEnv namespace. VSIZE( string ) VSIZE gives the storage size of string in Oracle. 938 Part VII: Alphabetical Reference ORACLE Series TIGHT / Oracle9 i : The Complete Reference / Loney, Koch / 222521-1 / Chapter 1 Blind Folio 1:938 P:\010Comp\Oracle8\521-1\CD\Ventura\ch42a.vp Thursday, July 25, 2002 3:53:28 PM Color profile: Generic CMYK printer profile Composite Default screen CHARTOROWID SEE ALSO CONVERSION FUNCTIONS, ROWIDTOCHAR FORMAT CHARTOROWID( string ) DESCRIPTION This stands for CHARacter TO ROW IDentifier. It changes a character string to act like an internal Oracle row identifier, or ROWID. CHECKPOINT A checkpoint is a point in time at which changed blocks of data are written from the SGA to the database. CHILD In tree-structured data, a child is a node that is the immediate descendant of another node. The node that the child descends from is called the parent. CHR SEE ALSO ASCII, CHARACTER FUNCTIONS FORMAT CHR( integer ) DESCRIPTION CHR will return the character with the ASCII value of integer. ( integer means an integer between 0 and 255, since the ASCII value of a character is an integer between 0 and 255.) Those between 0 and 127 are well defined. Those above 127 (called the extended ASCII set) tend to differ by country, application, and computer manufacturer. The letter A, for instance, is equal to the ASCII number 65, B is 66, C is 67, and so on. The decimal point is 46. A minus sign is 45. The number 0 is 48, 1 is 49, 2 is 50, and so on. EXAMPLE select CHR(77), CHR(46), CHR(56) from DUAL; C C C - - - M . 8 CLAUSE A clause is a major section of a SQL statement and begins with a keyword such as select, insert, update, delete, from, where, order by, group by,orhaving. CLEAR SEE ALSO BREAK, COLUMN, COMPUTE FORMAT CL[EAR] option DESCRIPTION CLEAR clears the option. BRE[AKS] clears breaks set by the BREAK command. BUFF[ER] clears the current buffer. CLEAR 939 ORACLE Series TIGHT / Oracle9 i : The Complete Reference / Loney, Koch / 222521-1 / Chapter 1 Blind Folio 1:939 P:\010Comp\Oracle8\521-1\CD\Ventura\ch42a.vp Thursday, July 25, 2002 3:53:29 PM Color profile: Generic CMYK printer profile Composite Default screen COL[UMNS] clears options set by the COLUMN command. COMP[UTES] clears options set by the COMPUTE command. SCR[EEN] clears the screen. SQL clears the SQL buffer. TIMI[NG] deletes all timing areas created by the TIMING command. EXAMPLES To clear computes, use this: clear computes To clear column definitions, use this: clear columns CLIENT Client is a general term for a user, software application, or computer that requires the services, data, or processing of another application or computer. CLOB CLOB is a datatype that supports character large objects. See Chapter 32. CLOSE SEE ALSO DECLARE, FETCH, FOR, OPEN, Chapter 27 FORMAT CLOSE cursor ; DESCRIPTION CLOSE closes the named cursor, and releases its resources to Oracle for use elsewhere. cursor must be the name of a currently open cursor. Even though a cursor has been closed, its definition has not been lost. You can issue OPEN cursor again, so long as the cursor was explicitly declared. A FOR loop will also implicitly OPEN a declared cursor. See CURSOR FOR LOOP. CLOSED DATABASE A closed database is a database that is associated with an instance (the database is mounted) but not open. Databases must be closed for some database maintenance functions. This can be accomplished via the SQL statement ALTER DATABASE. CLUSTER A cluster is a means of storing together data from multiple tables, when the data in those tables contains common information and is likely to be accessed concurrently. You can also cluster an individual table. See CREATE CLUSTER and Chapter 20. CLUSTER INDEX A cluster index is one manually created after a cluster has been created and before any DML (select, insert, update, or delete) statements can operate on the cluster. This index is created on the cluster key columns with the SQL statement CREATE INDEX. In Oracle, you can define a hash cluster to index on the primary key. See HASH CLUSTER. 940 Part VII: Alphabetical Reference ORACLE Series TIGHT / Oracle9 i : The Complete Reference / Loney, Koch / 222521-1 / Chapter 1 Blind Folio 1:940 P:\010Comp\Oracle8\521-1\CD\Ventura\ch42a.vp Thursday, July 25, 2002 3:53:30 PM Color profile: Generic CMYK printer profile Composite Default screen CLUSTER KEY A cluster key is the column or columns that clustered tables have in common, and which is chosen as the storage/access key. For example, two tables, BOOKSHELF and BOOKSHELF_AUTHOR, might be clustered on the column Title. A cluster key is the same thing as a CLUSTER COLUMN. CMDSEP (SQL*PLUS) See SET. COALESCE SEE ALSO DECODE, Chapter 17 FORMAT COALESCE( value1 , value2 , ) DESCRIPTION COALESCE will return the first non-NULL value encountered in the list of values provided. COALESCE (space) To coalesce space is to unite adjoining free extents into a single extent. For example, if two 100-block extents are next to each other within a tablespace, then they can be coalesced into a single 200-block extent. The SMON background process will coalesce free space within tablespaces whose default pctincrease value is non-zero. You can manually coalesce the free space within a tablespace via the coalesce option of the alter tablespace command. See ALTER TABLESPACE. COLLATION SEE ALSO GROUP BY, INDEX, ORDER BY, Chapter 9 DESCRIPTION The collation or collating sequence is the order in which characters, numbers, and symbols will be sorted because of an order by or group by clause. These sequences differ based on the collation sequence of the computer's operating system or the national language. EBCDIC (usually IBM and compatible mainframes) and ASCII (most other computers) sequences differ significantly. In spite of these differences, the following rules always apply: ■ A number with a larger value is considered "greater" than a smaller one. All negative numbers are smaller than all positive numbers. Thus, -10 is smaller than 10; -100 is smaller than -10. ■ A later date is considered greater than an earlier date. Character strings are compared position by position, starting at the leftmost end of the string, up to the first character that is different. Whichever string has the "greater" character in that position is considered the greater string. One character is considered greater than another if it appears after the other in the computer's collation sequence. Usually this means that a B is greater than an A, but the value of A compared to a, or compared to the number 1, will differ by computer. The collation comparison varies slightly depending on whether you are using CHAR or VARCHAR2 strings. If two VARCHAR2 strings are identical up to the end of the shorter one, the longer string is considered greater. If two strings are identical and the same length, they are considered equal. With CHAR strings, the shorter string is padded with blanks out to the length of the longer string. If the strings are not identical after this padding, the comparison treats the padded blanks as less than any other character, resulting in the same truth value as the VARCHAR2 comparison. If the strings are COLLATION 941 ORACLE Series TIGHT / Oracle9 i : The Complete Reference / Loney, Koch / 222521-1 / Chapter 1 Blind Folio 1:941 P:\010Comp\Oracle8\521-1\CD\Ventura\ch42a.vp Thursday, July 25, 2002 3:53:31 PM Color profile: Generic CMYK printer profile Composite Default screen identical after, but not before the padding, the CHAR comparison would treat them as equal whereas the VARCHAR2 comparison would not. In SQL it is important that literal numbers be typed without enclosing single quotes, as '10' would be considered smaller than '6', since the quotes will cause these to be regarded as character strings rather than numbers, and the '6' will be seen as greater than the '1' in the first position of '10'. COLSEP (SQL*PLUS) See SET. COLUMN (Form 1-Definition) A column is a subdivision of a table with a column name and a specific datatype. For example, in a table of workers, all of the worker's ages would constitute one column. See ROW. COLUMN (Form 2-SQL*PLUS) SEE ALSO ALIAS, Chapters 6 and 14 FORMAT COL[UMN] { column | expression } [ ALI[AS] alias ] [ CLE[AR] | DEF[AULT] ] [ ENTMAP {ON|OFF} [ FOLD_A[FTER] [ FOLD_B[EFORE] [ FOR[MAT] format ] [ HEA[DING] text [ JUS[TIFY] {L[EFT]|C[ENTER]|C[ENTRE]|R[IGHT]} ] ] [ LIKE { expression | alias } ] [ NEWL[INE] ] [ NEW_V[ALUE] variable ] [ NOPRI[NT]|PRI[NT] ] [ NUL[L] text ] [ ON | OFF ] [ OLD_V[ALUE] variable ] [ WRA[PPED]|WOR[D_WRAPPED]|TRU[NCATED] ] DESCRIPTION COLUMN controls column and column heading formatting. The options are all cumulative, and may be entered either simultaneously on a single line, or on separate lines at any time; the only requirement is that the word COLUMN and the column or expression must appear on each separate line. If one of the options is repeated, the most recent specified will be in effect. COLUMN by itself displays all the current definitions for all columns. COLU MN with only a column or expression will show that column's current definition. column or expression refers to a column or expression used in the select. If an expression is used, the expression must be entered exactly the same way that it is in the select statement. If the expression in the select is Amount * Rate, then entering Rate * Amount in a COLUMN command will not work. If a column or expression is given an alias in the select statement, that alias must be used here. If you select columns with the same name from different tables (in sequential selects), a COLUMN command for that column name will apply to both. Avoid this by assigning the columns different aliases 942 Part VII: Alphabetical Reference ORACLE Series TIGHT / Oracle9 i : The Complete Reference / Loney, Koch / 222521-1 / Chapter 1 Blind Folio 1:942 P:\010Comp\Oracle8\521-1\CD\Ventura\ch42a.vp Thursday, July 25, 2002 3:53:31 PM Color profile: Generic CMYK printer profile Composite Default screen in the select (not with the COLUMN command's alias clause), and entering a COLUMN command for each column's alias. ALIAS gives this column a new name, which then may be used to reference the column in BREAK and COLUMN commands. CLEAR drops the column definition. DEFAULT leaves the column defined and ON, but drops any other options. ENTMAP allows entity mapping to be turned on or off for selected columns in HTML output. FOLD_A[FTER] and FOLD_B[EFORE] instruct Oracle to fold a single row of output across multiple rows when printed. You can choose to fold the row either before or after the column. FORMAT specifies the display format of the column. The format must be a literal like A25 or 990.99. Without format specified, the column width is the length as defined inthe table. A LONG column’s width defaults to the value of the SET LONG. Both regular CHAR and LONG fields can have their width set by a format like FORMAT A n , where n is an integer that is the column’s new width. A number column’s width defaults to the value of SET NUMWIDTH, but is changed by the width in a format clause such as FORMAT 999,999.99. These options work with both set numformat and the column format commands: Format Result 9999990 The count of nines and zeros determines the maximum digits that can be displayed. 999,999,999.99 Commas and decimals will be placed in the pattern shown. 999990 Displays a zero if the value is zero. 099999 Displays numbers with leading zeros. $99999 A dollar sign is placed in front of every number. B99999 The display will be blank if the value is zero. 99999MI If the number is negative, a minus sign follows the number. The default is for the negative sign to be on left. S9999 Returns "+" for positive values, "-" for negative values. 99999PR Negative numbers are displayed within < and >. 99D99 Displays the decimal in the position indicated. 9G999 Displays the group separator in the position shown. C9999 Displays the ISO currency symbol in this position. L999 Displays the local currency symbol. , Displays a comma. . Displays a period. 9.999EEEE The display will be in scientific notation (4 E's are required). 999V99 Multiplies number by 10 n , where n is the number of digits to the right of V. 999V99 turns 1234 into 123400. RN Displays Roman numeral values, for numbers between 1 and 3999. DATE Displays value as a date in MM/DD/YY format, for NUMBER columns used storing Julian dates. COLUMN (Form 2-SQL*PLUS) 943 ORACLE Series TIGHT / Oracle9 i : The Complete Reference / Loney, Koch / 222521-1 / Chapter 1 Blind Folio 1:943 P:\010Comp\Oracle8\521-1\CD\Ventura\ch42a.vp Thursday, July 25, 2002 3:53:32 PM Color profile: Generic CMYK printer profile Composite Default screen HEADING relabels a column heading. The default is the column name or the expression. If text has blanks or punctuation characters, it must be in single quotes. The HEADSEP character (usually '|') in text makes SQL*PLUS begin a new line. The COLUMN command will remember the current HEADSEP character when the column is defined, and continue to use it for this column unless the column is redefined, even if the HEADSEP character is changed. JUSTIFY aligns the heading over the column. By default this is RIGHT for number columns and LEFT for anything else. LIKE replicates the column definitions of a previously defined column for the current one, where either the expression or label was used in the other column definition. Only those features of the other column that have not been explicitly defined in the current column command are copied. NEWLINE starts a new line before printing the column value. NEW_VALUE names a variable to hold the column's value for use in the ttitle command. See Chapter 14 for usage information. NOPRINT and PRINT turn the column's display off or on. NULL sets text to be displayed if the column has a NULL value. The default for this is a string of blanks as wide as the column is defined. OFF or ON turns all these options for a column off or on without affecting its contents. OLD_VALUE names a variable to hold the column's value for use in the btitle command. See Chapter 13 for usage information. WRAPPED, WORD_WRAPPED, and TRUNCATED control how SQL*PLUS displays a heading or string value too wide to fit the column. WRAP folds the value to the next line. WORD_WRAP folds similarly, but breaks on words. TRUNCATED truncates the value to the width of the column definition. COLUMN CONSTRAINT A column constraint is an integrity constraint placed on a specific column of a table. See INTEGRITY CONSTRAINT. COMMAND See STATEMENT. COMMAND LINE A command line is a line on a computer display where you enter a command. COMMENT SEE ALSO DATA DICTIONARY VIEWS, Chapter 37 FORMAT COMMENT ON { TABLE [ schema .] { table | view | materialized view } | COLUMN [ schema .] { table . | view . | materialized view . } column | OPERATOR [ schema .] operator | INDEXTYPE [ schema .] indextype } IS ' text '; 944 Part VII: Alphabetical Reference ORACLE Series TIGHT / Oracle9 i : The Complete Reference / Loney, Koch / 222521-1 / Chapter 1 Blind Folio 1:944 P:\010Comp\Oracle8\521-1\CD\Ventura\ch42a.vp Thursday, July 25, 2002 3:53:32 PM Color profile: Generic CMYK printer profile Composite Default screen DESCRIPTION COMMENT inserts the comment text about an object or column into the data dictionary. You drop a comment from the database only by setting it to an empty string (set text to ''). COMMIT To commit means to make changes to data (inserts, updates, and deletes) permanent. Before changes are stored, both the old and new data exist so that changes can be made, or so that the data can be restored to its prior state ("rolled back"). When a user enters the Oracle SQL command COMMIT, all changes from that transaction are made permanent. COMMIT (Form 1-Embedded SQL) SEE ALSO ROLLBACK, SAVEPOINT, SET TRANSACTION, Precompiler programmer's guides FORMAT EXEC SQL [AT { database | : host variable }] COMMIT [WORK] [ [COMMENT ' text ' ] [RELEASE] | FORCE ' text ' [, integer ]] DESCRIPTION You use COMMIT to commit work at various stages within a program. Without the explicit use of COMMIT, an entire program's work will be considered one transaction, and will not be committed until the program terminates. Any locks obtained will be held until that time, blocking other users from access. COMMIT should be used as often as logically feasible. WORK is optional and has no effect on usage; it is provided for ANSI compatibility. AT references a remote database accessed by the DECLARE DATABASE command. RELEASE disconnects you from the database, whether remote or local. FORCE manually commits an in-doubt distributed transaction. COMMIT (Form 2-PL/SQL Statement) SEE ALSO ROLLBACK, SAVEPOINT FORMAT COMMIT [WORK] [ COMMENT ' text ' | FORCE ' text ' [, integer ] ]; DESCRIPTION COMMIT commits any changes made to the database since the last COMMIT was executed implicitly or explicitly. WORK is optional and has no effect on usage. COMMENT associates a text comment with the transaction. The comment can be viewed via the data dictionary view DBA_2PC_PENDING in the event a distributed transaction fails to complete. FORCE manually commits an in-doubt distributed transaction. COMMUNICATIONS PROTOCOL Communications protocol is any one of a number of standard means of connecting two computers together so that they can share information. Protocols consist of several layers of both software and hardware, and may connect homogeneous or heterogeneous computers. COMMUNICATIONS PROTOCOL 945 ORACLE Series TIGHT / Oracle9 i : The Complete Reference / Loney, Koch / 222521-1 / Chapter 1 Blind Folio 1:945 P:\010Comp\Oracle8\521-1\CD\Ventura\ch42a.vp Thursday, July 25, 2002 3:53:33 PM Color profile: Generic CMYK printer profile Composite Default screen COMPOSE SEE ALSO CONVERSION FUNCTIONS, Chapter 10 FORMAT COMPOSE( string ) DESCRIPTION COMPOSE takes as its argument a string in any datatype, and returns a unicode string in its fully normalized form in the same character set as the input. EXAMPLE To display an o with an umlaut: select COMPOSE ( 'o' || UNISTR('\0308') ) from DUAL; C - ö COMPOSITE KEY A composite key is a primary or foreign key composed of two or more columns. COMPOSITE PARTITION A composite partition involves the use of multiple partition methods, such as a range-partitioned table in which the range partitions are then hash partitioned. See Chapter 18. COMPRESSED INDEX A compressed index is an index for which only enough index information is stored to identify unique index entries; information that an index stores with the previous or following key is "compressed" (truncated) and not stored to reduce the storage overhead required by an index. See also NONCOMPRESSED INDEX. COMPUTE SEE ALSO BREAK, GROUP FUNCTIONS FORMAT COMP[UTE][AVG|COU[NT]|MAX[IMUM]|MIN[IMUM]|NUM[BER]|STD|SUM|VAR[IANCE]] [ function LABEL label_name OF { expression | column | alias } ON { expression | column | alias | REPORT | ROW} ] DESCRIPTION expression is a column or expression. COMPUTE performs computations on columns or expressions selected from a table. It works only with the BREAK command. By default, Oracle will use the function name (SUM, AVG, etc.) as the label for the result in the query output. LABEL allows you to specify a label_name that overrides the default value. OF names the column or expression whose value is to be computed. These columns also must be in the select clause, or the COMPUTE will be ignored. 946 Part VII: Alphabetical Reference ORACLE Series TIGHT / Oracle9 i : The Complete Reference / Loney, Koch / 222521-1 / Chapter 1 Blind Folio 1:946 P:\010Comp\Oracle8\521-1\CD\Ventura\ch42a.vp Thursday, July 25, 2002 3:53:34 PM Color profile: Generic CMYK printer profile Composite Default screen ON coordinates the COMPUTE with the BREAK command. COMPUTE prints the computed value and restarts the computation when the ON expression 's value changes, or when a specified ROW or REPORT break occurs. See BREAK for coordination details. COMPUTE by itself displays the computes in effect. AVG, MAXIMUM, MINIMUM, STD, SUM, and VARIANCE all work on expressions that are numbers. MAXIMUM and MINIMUM also work on character expressions, but not DATEs. COUNT and NUMBER work on any expression type. All of these computes except NUMBER ignore rows with NULL values: AVG Gives average value COUNT Gives count of non-NULL values MAXIMUM Gives maximum value MINIMUM Gives minimum value NUMBER Gives count of all rows returned STD Gives standard deviation SUM Gives sum of non-NULL values VARIANCE Gives variance Successive computes are simply put in order without commas, such as in this case: compute sum avg max of Amount Rate on report This will compute the sum, average, and maximum of both Amount and Rate for the entire report. EXAMPLE To calculate for each Item classification and for the entire report, enter this: break on Report on Industry skip 1 compute sum of Volume on Industry Report CONCAT See SET, ||. CONCATENATED INDEX (or KEY) A concatenated index is one that is created on more than one column of a table. It can be used to guarantee that those columns are unique for every row in the table and to speed access to rows via those columns. See COMPOSITE KEY. CONCURRENCY Concurrency is a general term meaning the access of the same data by multiple users. In database software, concurrency requires complex software programming to assure that all users see correct data and that all changes are made in the proper order. CONCURRENCY 947 ORACLE Series TIGHT / Oracle9 i : The Complete Reference / Loney, Koch / 222521-1 / Chapter 1 Blind Folio 1:947 P:\010Comp\Oracle8\521-1\CD\Ventura\ch42a.vp Thursday, July 25, 2002 3:53:35 PM Color profile: Generic CMYK printer profile Composite Default screen [...]... optional Oracle Net string (such as a service name) used during the connect operation Without the USING string, you will be connected to the user's default database, regardless of the database named in the AT line P:\010Comp \Oracle8 \521-1\CD\Ventura\ch42a.vp Thursday, July 25, 2002 3:53:36 PM ORACLE Color profile: Generic CMYK printer profile Composite Default screen Series TIGHT / Oracle9 i: The Complete Reference. .. screen Series TIGHT / Oracle9 i: The Complete Reference / Loney, Koch / 222521-1 / Chapter 1 Blind Folio 1:951 constraints out_of_line_ref_constraint references_clause::= constraint_state::= P:\010Comp \Oracle8 \521-1\CD\Ventura\ch42b.vp Friday, July 19, 2002 1:47:15 PM 951 ORACLE Color profile: Generic CMYK printer profile Composite Default screen 952 Series TIGHT / Oracle9 i: The Complete Reference / Loney,... key Instead, Oracle uses a hash function to store the rows of the table You can create your own hash value as a column of the table and use that for hashing with the HASH IS clause to tell Oracle to use that column as the hash value Otherwise, Oracle uses an internal hash function based on the columns of the cluster key The HASHKEYS clause actually creates the hash cluster and specifies the number of... command The REUSE option lets existing control files be reused rather than giving an error if any exist The SET option changes the name of the database, specified by the database clause The LOGFILE clause specifies the redo log file groups, all of which must exist The RESETLOGS versus NORESETLOGS clause tells Oracle to reset the current logs or not The DATAFILE line specifies the data files for the database,... another computer using Oracle Net FROM is the user name, password, and database of the source table, and TO is the destination table Either FROM or TO may be omitted, in which case the user’s default database will be used for the missing clause The source and destination databases must not be the same, so only one of the from and to clauses may be absent APPEND adds to the destination table; if the. .. option gives the maximum number of Oracle instances that can mount and open the database The ARCHIVELOG and NOARCHIVELOG options turns archiving of the redo log files on and off, respectively P:\010Comp \Oracle8 \521-1\CD\Ventura\ch42b.vp Friday, July 19, 2002 1:47:27 PM 961 ORACLE Color profile: Generic CMYK printer profile Composite Default screen 962 Series TIGHT / Oracle9 i: The Complete Reference /... TIGHT / Oracle9 i: The Complete Reference / Loney, Koch / 222521-1 / Chapter 1 Blind Folio 1:969 CREATE INDEX cluster_index_clause::= table_index_clause::= bitmap_join_index_clause::= index_expr::= P:\010Comp \Oracle8 \521-1\CD\Ventura\ch42b.vp Friday, July 19, 2002 1:47:49 PM 969 ORACLE Color profile: Generic CMYK printer profile Composite Default screen 970 Series TIGHT / Oracle9 i: The Complete Reference. .. column, is the name(s) of the column(s) in the destination table If named, the number of columns must be the same as in the query If no columns are named, the copied columns will have the same names in the destination table as they had in the source table query identifies the source table and determines which rows and columns will be copied from it SET LONG (see SET) determines the length of a long field... added to the cluster using CREATE TABLE with the cluster clause CREATE CLUSTER requires at least one cluster column from each of the tables These must have the same datatype and size, but are not required to have the same name For the tables in a cluster, rows with the same cluster column values are kept together on disk in the same area, the same logical block(s) This can improve performance when the cluster... START WITH tells where in the tree to begin These are the rules: s The position of PRIOR with respect to the CONNECT BY expressions determines which expression identifies the root and which identifies the branches of the tree s A where clause will eliminate individuals from the tree, but not their descendants (or ancestors, depending on the location of PRIOR) s A qualification in the CONNECT BY (particularly . the columns different aliases 942 Part VII: Alphabetical Reference ORACLE Series TIGHT / Oracle9 i : The Complete Reference / Loney, Koch / 222521-1 / Chapter 1 Blind Folio 1:942 P:10Comp Oracle8 521-1CDVenturach42a.vp Thursday,. named in the AT line. 948 Part VII: Alphabetical Reference ORACLE Series TIGHT / Oracle9 i : The Complete Reference / Loney, Koch / 222521-1 / Chapter 1 Blind Folio 1:948 P:10Comp Oracle8 521-1CDVenturach42a.vp Thursday,. CLUSTER. 940 Part VII: Alphabetical Reference ORACLE Series TIGHT / Oracle9 i : The Complete Reference / Loney, Koch / 222521-1 / Chapter 1 Blind Folio 1:940 P:10Comp Oracle8 521-1CDVenturach42a.vp Thursday,