Firebird 2.1 Language Reference Update

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DML statements • Only non-negative whole number literals are interpreted as column positions. A whole number resulting from an expression evaluation or parameter substitution is seen as an integer invariable and will lead to a dummy sort, since its value is the same for each row. NULLs placement Changed in: 1.5, 2.0 Description: Firebird 1.5 has introduced the per-column NULLS FIRST and NULLS LAST directives to specify where NULLs appear in the sorted column. Firebird 2.0 has changed the default placement of NULLs. Unless overridden by NULLS FIRST or NULLS LAST, NULLs in ordered columns are placed as follows: • In Firebird 1.0 and 1.5: at the end of the sort, regardless whether the order is ascending or descending. • In Firebird 2.0 and up: at the start of ascending orderings and at the end of descending orderings. See also the table below for an overview of the different versions. Table 6.1. NULLs placement in ordered columns Ordering 79 NULLs placement Firebird 1 Firebird 1.5 Firebird 2 order by Field [asc] bottom bottom top order by Field desc bottom bottom bottom order by Field [asc | desc] nulls first — top top order by Field [asc | desc] nulls last — bottom bottom Examples: Notes • Pre-existing databases may need a backup-restore cycle before they show the correct NULL ordering behaviour under Firebird 2.0 and up. • No index will be used on columns for which a non-default NULLS placement is chosen. In Firebird 1.5, that is the case with NULLS FIRST. In 2.0 and higher, with NULLS LAST on ascending and NULLS FIRST on descending sorts. select * from msg order by process_time desc nulls first select * from document order by strlen(description) desc rows 10 select doc_number, doc_date from payorder union all select doc_number, doc_date from budgorder order by 2 desc nulls last, 1 asc nulls first
DML statements Stricter ordering rules with aggregate statements Changed in: 1.5 Description: See Aggregate statements: Stricter HAVING and ORDER BY. PLAN Available in: DSQL, ESQL, PSQL Description: Specifies a user plan for the data retrieval, overriding the plan that the optimizer would have generated automatically. Syntax: PLAN ::= [JOIN | [SORT] [MERGE]] ( [, ...]) ::= | ::= {table | alias} {NATURAL | INDEX ()) | ORDER index [INDEX ()]} ::= index [, index ...] Handling of user PLANs improved Changed in: 2.0 Description: Firbird 2 has implemented the following improvements in the handling of user-specified PLANs: • Plan fragments are propagated to nested levels of joins, enabling manual optimization of complex outer joins. • User-supplied plans will be checked for correctness in outer joins. • Short-circuit optimization for user-supplied plans has been added. • A user-specified access path can be supplied for any SELECT-based statement or clause. ORDER with INDEX Changed in: 2.0 Description: A single plan item can now contain both an ORDER and an INDEX directive (in that order). 80
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Firebird 2.1 Language Reference Upd
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Table of Contents 1. Introduction .
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Firebird 2.1 Language Ref. Update F
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Firebird 2.1 Language Ref. Update A
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Firebird 2.1 Language Ref. Update s
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Chapter 1 Introduction Subject matt
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Chapter 2 Reserved words and keywor
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LOCK LOG LOG10 LPAD MATCHED MATCHIN
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Chapter 3 Available in: DSQL, PSQL
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Example: select name, age, case upp
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Data types and subtypes • Partial
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Added in: 1.0, 1.5, 1.5.1, 2.0, 2.1
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Chapter 5 DDL statements The statem
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With a special attribute (case-sens
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DIFFERENCE FILE parameter Added in:
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CREATE DOMAIN Available in: DSQL, E
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Example: DDL statements create exce
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Syntax: Example: ALTER EXTERNAL FUN
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DDL statements -- the following que
Page 40 and 41: DDL statements PROCEDURE A stored p
Page 42 and 43: DDL statements Description: Firebir
Page 44 and 45: DDL statements NOT NULL in variable
Page 46 and 47: CREATE GENERATOR Available in: DSQL
Page 48 and 49: Better alternative: DROP SEQUENCE D
Page 50 and 51: ) DDL statements lastname varchar(2
Page 52 and 53: USING INDEX subclause Available in:
Page 54 and 55: ALTER COLUMN: SET DEFAULT Available
Page 56 and 57: UNIQUE constraints now allow NULLs
Page 58 and 59: Example: DDL statements create trig
Page 60 and 61: Multi-action triggers Added in: 1.5
Page 62 and 63: NOT NULL in variable declarations C
Page 64 and 65: DDL statements Restriction on recre
Page 66 and 67: DDL statements got a chance to put
Page 68 and 69: ORDER BY Available in: DSQL, PSQL A
Page 70 and 71: DML statements ROWS can also be use
Page 72 and 73: DML statements COLLATE in variable
Page 74 and 75: The same call in ESQL (with obligat
Page 76 and 77: DML statements Description: A SELEC
Page 78 and 79: DML statements Aggregate functions
Page 80 and 81: Syntax: Example: Notes: ::= DML
Page 82 and 83: DML statements select d.dept_no, d.
Page 84 and 85: DML statements FIRST and SKIP are b
Page 86 and 87: DML statements select strlen(lastna
Page 88 and 89: DML statements Description: A natur
Page 92 and 93: Example: DML statements plan (MyTab
Page 94 and 95: UNIONs in subqueries Changed in: 2.
Page 96 and 97: Restrictions DML statements • The
Page 98 and 99: DML statements Description: Limits
Page 100 and 101: Chapter 7 Available in: DSQL Added
Page 102 and 103: Transaction control statements If t
Page 104 and 105: Transaction control statements •
Page 106 and 107: Chapter 8 PSQL statements PSQL - Pr
Page 108 and 109: PSQL statements • If sql_datatype
Page 110 and 111: Warning PSQL statements If you chan
Page 112 and 113: PSQL statements exception ex_bad_ty
Page 114 and 115: PSQL statements as declare variable
Page 116 and 117: Examples: PSQL statements thoroughl
Page 118 and 119: leave; end end c = 0; PSQL statemen
Page 120 and 121: Chapter 9 Available in: DSQL, PSQL
Page 122 and 123: Changed in: 2.0 Context variables D
Page 124 and 125: Context variables its execution was
Page 126 and 127: Context variables Description: OLD
Page 128 and 129: Chapter 10 Changed in: 2.0 Operator
Page 130 and 131: UNION as subselect Changed in: 2.0
Page 132 and 133: Chapter 11 Aggregate functions Aggr
Page 134 and 135: Chapter 12 Available in: DSQL, PSQL
Page 136 and 137: • If the argument is NULL, NULL i
Page 138 and 139: Result type: INTEGER or BIGINT Synt
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Result type: INTEGER Syntax: BIT_LE
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Internal functions This gives you c
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Available in: DSQL, PSQL Added in:
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Example: The equivalent CASE constr
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WEEK Bug alert Internal functions M
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Added in: 2.1 Internal functions De
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Internal functions • If x is nega
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Examples: Internal functions lpad (
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Internal functions This will return
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Internal functions overlay ('Goodby
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Internal functions Description: Cre
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Internal functions reverse ('Was it
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Added in: 2.1 Internal functions De
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Syntax: SINH (number) Important Int
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Notes: Internal functions • If th
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Description: Returns the arc cosine
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Declaration: External functions (UD
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Library: ib_udf Changed in: 1.0, 2.
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Better alternative: Internal functi
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External functions (UDFs) Descripti
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Syntax: cot (angle) Declaration: Ex
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Declaration: External functions (UD
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Library: ib_udf Added in: IB Change
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Changed in: 1.5, 1.5.2, 2.0 Better
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External functions (UDFs) DECLARE E
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See sright. Library: fbudf Added in
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Notes: External functions (UDFs) Fo
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Syntax: sign (number) Declaration:
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Library: fbudf Added in: 1.0 (Win),
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Notes: External functions (UDFs) th
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Better alternative: Internal functi
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Appendix A: Notes Character set NON
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Table A.1. How TPB settings affect
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Notes A note on CSTRING parameters
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Notes Maximum number of indices in
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Document History DDL statements ::
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Document History Internal functions
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Appendix C: License notice The cont
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Firebird 2.1 Language Reference Update

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