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Add IS UNKNOWN, IS NOT UNKNOWN boolean tests, fix the existing boolean

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tests to return the correct results per SQL9x when given NULL inputs.
Reimplement these tests as well as IS [NOT] NULL to have their own
expression node types, instead of depending on special functions.
From Joe Conway, with a little help from Tom Lane.
This commit is contained in:
Tom Lane
2001-06-19 22:39:12 +00:00
parent 8c30aca2ba
commit 116d2bba7e
18 changed files with 666 additions and 153 deletions
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51
src/include/nodes/parsenodes.h
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@@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2001, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $Id: parsenodes.h,v 1.131 2001/06/09 23:21:55 petere Exp $
* $Id: parsenodes.h,v 1.132 2001/06/19 22:39:12 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@@ -983,9 +983,8 @@ typedef struct ParamNo
typedef struct A_Expr
{
NodeTag type;
int oper; /* type of operation
* {OP,OR,AND,NOT,ISNULL,NOTNULL} */
char *opname; /* name of operator/function */
int oper; /* type of operation (OP,OR,AND,NOT) */
char *opname; /* name of operator */
Node *lexpr; /* left argument */
Node *rexpr; /* right argument */
} A_Expr;
@@ -1054,6 +1053,50 @@ typedef struct CaseWhen
Node *result; /* substitution result */
} CaseWhen;
/* ----------------
* NullTest
*
* NullTest represents the operation of testing a value for NULLness.
* Currently, we only support scalar input values, but eventually a
* row-constructor input should be supported.
* The appropriate test is performed and returned as a boolean Datum.
* ----------------
*/
typedef enum NullTestType
{
IS_NULL, IS_NOT_NULL
} NullTestType;
typedef struct NullTest
{
NodeTag type;
Node *arg; /* input expression */
NullTestType nulltesttype; /* IS NULL, IS NOT NULL */
} NullTest;
/* ----------------
* BooleanTest
*
* BooleanTest represents the operation of determining whether a boolean
* is TRUE, FALSE, or UNKNOWN (ie, NULL). All six meaningful combinations
* are supported. Note that a NULL input does *not* cause a NULL result.
* The appropriate test is performed and returned as a boolean Datum.
* ----------------
*/
typedef enum BoolTestType
{
IS_TRUE, IS_NOT_TRUE, IS_FALSE, IS_NOT_FALSE, IS_UNKNOWN, IS_NOT_UNKNOWN
} BoolTestType;
typedef struct BooleanTest
{
NodeTag type;
Node *arg; /* input expression */
BoolTestType booltesttype; /* test type */
} BooleanTest;
/*
* ColumnDef - column definition (used in various creates)
*