v_table_ddl :=v_table_ddl||'COMMENT ON CONSTRAINT "'||v_constraint_comment_record.conname||'" ON "'||in_table_name||'" IS '''||replace(v_constraint_comment_record.description,''',''')||''';'||E'\n';ENDLOOP;-- return the ddlRETURNv_table_ddl;END$$; 使用 selectshow_crea...
postgres=# \help SELECT Command: SELECT Description: retrieve rows from a table or view Syntax: [ WITH [ RECURSIVE ] with_query [, ...] ] SELECT [ ALL | DISTINCT [ ON ( expression [, ...] ) ] ] [ * | expression [ [ AS ] output_name ] [, ...] ] [ FROM from_item [,...
Usage of CONSTRAINTS SQL allows defining constraints on columns and tables. SQL rejects any value that violates the criteria that were defined. The column constraints apply only to individual columns. The table constraints apply to groups of one or more columns. The constraints are declared at the...
代码如下: 1CREATEORREPLACEFUNCTION"public"."showcreatetable"("dbinstancename"varchar, "namespace"varchar, "tablename"varchar, "tenantid"varchar)2RETURNS"pg_catalog"."varchar"AS$BODY$3declare4tableScriptcharactervaryingdefault'';5indexScripecharactervaryingdefault'';6constraintScripecharactervaryingdefault'...
CREATETABLEon_hand(item inventory_item,count integer);INSERTINTOon_handVALUES(ROW('fuzzy dice',42,1.99),1000); 复合类型值输入 要以文本常量书写复合类型值,在圆括弧里包围字段值并且用逗号分隔他们。 你可以在任何字段值周围放上双引号,如果值本身包含逗号或者圆括弧, 你必须用双引号括起。
Command:CREATETRIGGERDescription:define anewtriggerSyntax:CREATE[CONSTRAINT]TRIGGERname{BEFORE|AFTER|INSTEADOF}{event[OR...]}ONtable_name[FROMreferenced_table_name]{NOTDEFERRABLE|[DEFERRABLE]{INITIALLYIMMEDIATE|INITIALLYDEFERRED}}[FOR[EACH]{ROW|STATEMENT}][WHEN(condition)]EXECUTEPROCEDUREfunction_name(argume...
# SET NULL 主表在 on delete/update 时,设置从表外键为 NULL。 # SET DEFAULT 主表在 on delete/update 时,设置从表外键为 DEFAULT(默认值)。 CREATE TABLE products ( product_no integer PRIMARY KEY, name text, price numeric ); CREATE TABLE orders ( order_id integer PRIMARY KEY, shipping_addres...
[ ONLY ] table_name [ * ] [ [ AS ] alias [ ( column_alias [, ...] ) ] ] 更多关于大数据 PostgreSQL 系列的学习文章,请参阅:PostgreSQL 数据库,本系列持续更新中。 SQL 语句[2] 一个SQL 语句通常包含了关键字、标识符(字段)、常量、特殊符号等,下面是一个简单的 SQL 语句: ...
ccu.table_name AS foreign_table_name, ccu.column_name AS foreign_column_name FROM information_schema.table_constraints AS tc JOIN information_schema.key_column_usage AS kcu ON tc.constraint_name = kcu.constraint_name JOIN information_schema.constraint_column_usage AS ccu ON ccu.constraint_na...
rebuild_constraints,优先采用这种方式 它先通过alter table t2 drop fk1,add _fk1重建外键参考,指向新表 再rename t1 t1_old, _t1_new t1,交换表名,不影响客户端 删除旧表 t1_old 但如果字表t2太大,以致alter操作可能耗时过长,有可能会强制选择 drop_swap。