"ck_tbl_check_a" CHECK (a > 0) "ck_tbl_check_b" CHECK (b::text = ANY (ARRAY['ab'::character varying, 'aB'::character varying, 'Ab'::character varying, 'AB'::character varying]::text[]))*/ 2.以上表tbl_check为例,INSERT时a的值必须是大于0的整数,b的值只能在'ab','aB','Ab...
数据库表有NOT NULL,DEFAULT,CHECK,UNIQUE,PRIMARY KEY,FOREIGN KEY六种约束。 一、NOT NULL --- 非空约束 NULL表示没有数据,不表示具体的数值,所以在数据库中NULL是不等于NULL的。判断表中的一个单元格是不是NULL使用的是IS NULL或者IS NOT NULL,而不是=NULL或者!=NULL,当一个字段设置NOT NULL约束后,INSER...
WHEN 'f' THEN 'FOREIGN KEY' WHEN 'p' THEN 'PRIMARY KEY' WHEN 'u' THEN 'UNIQUE' END AS "constraint_type", CASE WHEN c.condeferrable = 'f' THEN 0 ELSE 1 END AS is_deferrable, CASE WHEN c.condeferred = 'f' THEN 0 ELSE 1 END AS is_deferred, t.relname AS table_name, array_...
CREATE OR REPLACE FUNCTION "public"."f_inittables1"(arr _text)RETURNS "pg_catalog"."void" AS $BODY$DECLAREscount INTEGER;rownum integer := 1;currsnum text;strSQL text;BEGINscount:=array_length(arr,1);while rownum <= scount LOOPcurrsnum:=arr[rownum];RAISE NOTICE '这里是%', currsnum...
WHEN'p'THEN'PRIMARY KEY' WHEN'u'THEN'UNIQUE' ENDAS"constraint_type", CASEWHENc.condeferrable = 'f'THEN0 ELSE1 ENDASis_deferrable, CASEWHENc.condeferred = 'f'THEN0 ELSE1 ENDASis_deferred, t.relname AStable_name, array_to_string(c.conkey, ' ') ASconstraint_key, ...
{ "array_subscript_error", ERRCODE_ARRAY_SUBSCRIPT_ERROR }, { "character_not_in_repertoire", ERRCODE_CHARACTER_NOT_IN_REPERTOIRE }, { "datetime_field_overflow", ERRCODE_DATETIME_FIELD_OVERFLOW }, { "division_by_zero", ERRCODE_DIVISION_BY_ZERO }, { "error_in_assignment", ERRCODE_ERROR_IN...
3)Maintenance_work_mem:用于限制vacuum、create index、reindex、alter table add foreign key所使用的最大内存量。 由于每个session只能执行这些操作中的一个,而且PG也会限制这些操作同时执行,所以Maintenance_work_mem可以比work_mem设置的更大一些。 注:当autovacuum运行时,可能会分配多达autovacuum_max_workers次的内...
pg_catalog | array_length | integer | anyarray, integer | normal pg_catalog | bit_length | integer | bit | normal pg_catalog | bit_length | integer | bytea | normal pg_catalog | bit_length | integer | text | normal pg_catalog | char_length | integer | character | normal ...
CREATE OR REPLACE FUNCTION generate_random_string(length INTEGER) RETURNS VARCHAR LANGUAGE plpgsql AS $$ DECLARE result VARCHAR(255) := ''; chars TEXT[] := ARRAY['a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v'...
(d.encoding)as"Encoding",d.datcollateas"Collate",d.datctypeas"Ctype",pg_catalog.array_to_string(d.datacl,E'\n')AS"Access privileges"FROMpg_catalog.pg_databasedORDERBY1;***ListofdatabasesName|Owner|Encoding|Collate|Ctype|Accessprivileges---+---+---+---+---+---postgres|postgres|UTF...