constraints.source

关系型数据库 Postgresql 6.5.2

--
-- Check constraints
-- Constraints can be specified with:
--  - DEFAULT clause
--  - CHECK clauses
--  - PRIMARY KEY clauses
--  - UNIQUE clauses
--

--
-- DEFAULT syntax
--

CREATE TABLE DEFAULT_TBL (i int DEFAULT 100,
	x text DEFAULT 'vadim', f float8 DEFAULT 123.456);

INSERT INTO DEFAULT_TBL VALUES (1, 'thomas', 57.0613);
INSERT INTO DEFAULT_TBL VALUES (1, 'bruce');
INSERT INTO DEFAULT_TBL (i, f) VALUES (2, 987.654);
INSERT INTO DEFAULT_TBL (x) VALUES ('marc');
INSERT INTO DEFAULT_TBL VALUES (3, null, 1.0);

SELECT '' AS five, * FROM DEFAULT_TBL;

CREATE SEQUENCE DEFAULT_SEQ;

CREATE TABLE DEFAULTEXPR_TBL (i1 int DEFAULT 100 + (200-199) * 2,
	i2 int DEFAULT nextval('default_seq'));

INSERT INTO DEFAULTEXPR_TBL VALUES (-1, -2);
INSERT INTO DEFAULTEXPR_TBL (i1) VALUES (-3);
INSERT INTO DEFAULTEXPR_TBL (i2) VALUES (-4);
INSERT INTO DEFAULTEXPR_TBL (i2) VALUES (NULL);

SELECT '' AS four, * FROM DEFAULTEXPR_TBL;

-- errors
-- test for:
--  extraneous comma
--  booleans not allowed
CREATE TABLE error_tbl (i int DEFAULT (100, ));
CREATE TABLE error_tbl (b1 bool DEFAULT 1 < 2);

--
-- CHECK syntax
--

CREATE TABLE CHECK_TBL (x int,
	CONSTRAINT CHECK_CON CHECK (x > 3));

INSERT INTO CHECK_TBL VALUES (5);
INSERT INTO CHECK_TBL VALUES (4);
INSERT INTO CHECK_TBL VALUES (3);
INSERT INTO CHECK_TBL VALUES (2);
INSERT INTO CHECK_TBL VALUES (6);
INSERT INTO CHECK_TBL VALUES (1);

SELECT '' AS three, * FROM CHECK_TBL;

CREATE SEQUENCE CHECK_SEQ;

CREATE TABLE CHECK2_TBL (x int, y text, z int,
	CONSTRAINT SEQUENCE_CON
	CHECK (x > 3 and y <> 'check failed' and z < 8));

INSERT INTO CHECK2_TBL VALUES (4, 'check ok', -2);
INSERT INTO CHECK2_TBL VALUES (1, 'x check failed', -2);
INSERT INTO CHECK2_TBL VALUES (5, 'z check failed', 10);
INSERT INTO CHECK2_TBL VALUES (0, 'check failed', -2);
INSERT INTO CHECK2_TBL VALUES (6, 'check failed', 11);
INSERT INTO CHECK2_TBL VALUES (7, 'check ok', 7);

SELECT '' AS two, * from CHECK2_TBL;

--
-- Check constraints on INSERT
--

CREATE SEQUENCE INSERT_SEQ;

CREATE TABLE INSERT_TBL (x INT DEFAULT nextval('insert_seq'),
	y TEXT DEFAULT '-NULL-', z INT DEFAULT -1 * currval('insert_seq'),
	CONSTRAINT INSERT_CON CHECK (x >= 3 AND y <> 'check failed' AND x < 8), 
		CHECK (x + z = 0));

INSERT INTO INSERT_TBL VALUES (null, null, null);
INSERT INTO INSERT_TBL(x,z) VALUES (2, -2);

SELECT '' AS zero, * FROM INSERT_TBL;

SELECT 'one' AS one, nextval('insert_seq');

INSERT INTO INSERT_TBL(y) VALUES ('Y');
INSERT INTO INSERT_TBL(y) VALUES ('Y');
INSERT INTO INSERT_TBL(x,z) VALUES (1, -2);
INSERT INTO INSERT_TBL(z,x) VALUES (-7,  7);
INSERT INTO INSERT_TBL VALUES (5, 'check failed', -5);
INSERT INTO INSERT_TBL VALUES (7, '!check failed', -7);
INSERT INTO INSERT_TBL(y) VALUES ('-!NULL-');

SELECT '' AS four, * FROM INSERT_TBL;

INSERT INTO INSERT_TBL(y,z) VALUES ('check failed', 4);
INSERT INTO INSERT_TBL(x,y) VALUES (5, 'check failed');
INSERT INTO INSERT_TBL(x,y) VALUES (5, '!check failed');
INSERT INTO INSERT_TBL(y) VALUES ('-!NULL-');

SELECT '' AS six, * FROM INSERT_TBL;

SELECT 'seven' AS one, nextval('insert_seq');

INSERT INTO INSERT_TBL(y) VALUES ('Y');

SELECT 'eight' AS one, currval('insert_seq');

--
-- Check constraints on INSERT INTO
--

DELETE FROM INSERT_TBL;
DROP SEQUENCE INSERT_SEQ;

CREATE SEQUENCE INSERT_SEQ START 4;

CREATE TABLE tmp (xd INT, yd TEXT, zd INT);

INSERT INTO tmp VALUES (null, 'Y', null);
INSERT INTO tmp VALUES (5, '!check failed', null);
INSERT INTO tmp VALUES (null, 'try again', null);
INSERT INTO INSERT_TBL(y) select yd from tmp;

SELECT '' AS three, * FROM INSERT_TBL;

INSERT INTO INSERT_TBL SELECT * FROM tmp WHERE yd = 'try again';
INSERT INTO INSERT_TBL(y,z) SELECT yd, -7 FROM tmp WHERE yd = 'try again';
INSERT INTO INSERT_TBL(y,z) SELECT yd, -8 FROM tmp WHERE yd = 'try again';

SELECT '' AS four, * FROM INSERT_TBL;

DROP TABLE tmp;

--
-- Check constraints on UPDATE
--

UPDATE INSERT_TBL SET x = NULL WHERE x = 6;
UPDATE INSERT_TBL SET x = 6 WHERE x = 6;
UPDATE INSERT_TBL SET x = -z, z = -x;
UPDATE INSERT_TBL SET x = z, z = x;

SELECT * FROM INSERT_TBL;

-- DROP TABLE INSERT_TBL;

--
-- Check constraints on COPY FROM
--

CREATE TABLE COPY_TBL (x INT, y TEXT, z INT,
	CONSTRAINT COPY_CON
	CHECK (x > 3 AND y <> 'check failed' AND x < 7 ));

COPY COPY_TBL FROM '_OBJWD_/data/constro.data';

SELECT '' AS two, * FROM COPY_TBL;

COPY COPY_TBL FROM '_OBJWD_/data/constrf.data';

SELECT * FROM COPY_TBL;

--
-- Primary keys
--

CREATE TABLE PRIMARY_TBL (i int PRIMARY KEY, t text);

INSERT INTO PRIMARY_TBL VALUES (1, 'one');
INSERT INTO PRIMARY_TBL VALUES (2, 'two');
INSERT INTO PRIMARY_TBL VALUES (1, 'three');
INSERT INTO PRIMARY_TBL VALUES (4, 'three');
INSERT INTO PRIMARY_TBL VALUES (5, 'one');
INSERT INTO PRIMARY_TBL (t) VALUES ('six');

SELECT '' AS four, * FROM PRIMARY_TBL;

DROP TABLE PRIMARY_TBL;

CREATE TABLE PRIMARY_TBL (i int, t text,
	PRIMARY KEY(i,t));

INSERT INTO PRIMARY_TBL VALUES (1, 'one');
INSERT INTO PRIMARY_TBL VALUES (2, 'two');
INSERT INTO PRIMARY_TBL VALUES (1, 'three');
INSERT INTO PRIMARY_TBL VALUES (4, 'three');
INSERT INTO PRIMARY_TBL VALUES (5, 'one');
INSERT INTO PRIMARY_TBL (t) VALUES ('six');

SELECT '' AS three, * FROM PRIMARY_TBL;

DROP TABLE PRIMARY_TBL;

--
-- Unique keys
--

CREATE TABLE UNIQUE_TBL (i int UNIQUE, t text);

INSERT INTO UNIQUE_TBL VALUES (1, 'one');
INSERT INTO UNIQUE_TBL VALUES (2, 'two');
INSERT INTO UNIQUE_TBL VALUES (1, 'three');
INSERT INTO UNIQUE_TBL VALUES (4, 'four');
INSERT INTO UNIQUE_TBL VALUES (5, 'one');
INSERT INTO UNIQUE_TBL (t) VALUES ('six');
INSERT INTO UNIQUE_TBL (t) VALUES ('seven');

SELECT '' AS five, * FROM UNIQUE_TBL;

DROP TABLE UNIQUE_TBL;

CREATE TABLE UNIQUE_TBL (i int, t text,
	UNIQUE(i,t));

INSERT INTO UNIQUE_TBL VALUES (1, 'one');
INSERT INTO UNIQUE_TBL VALUES (2, 'two');
INSERT INTO UNIQUE_TBL VALUES (1, 'three');
INSERT INTO UNIQUE_TBL VALUES (1, 'one');
INSERT INTO UNIQUE_TBL VALUES (5, 'one');
INSERT INTO UNIQUE_TBL (t) VALUES ('six');

SELECT '' AS five, * FROM UNIQUE_TBL;

DROP TABLE UNIQUE_TBL;