PostgreSQL获取建表语句存储过程

Posted 2021-09-10 diuxie

PG版本：

PostgreSQL 11.11

存储过程：

create or replace function get_tab_ddl(tab_name varchar)returns text as $$declare

--定义变量

tab_ddl text;

curs refcursor;

tmp_col record;

tab_info record;begin 

--获取表的pid、schema信息

open curs for SELECT c.oid,n.nspname,c.relname FROM pg_catalog.pg_class c    LEFT JOIN pg_catalog.pg_namespace n ON n.oid = c.relnamespace    WHERE c.relname ~ (\'^(\'||tab_name||\')$\')AND pg_catalog.pg_table_is_visible(c.oid) ORDER BY 2,3;

fetch curs into tmp_col;

--判断是否存在该表

if tmp_col.oid is null then

    return \'Table "\'||tab_name||\'" was not queried\';

end if;

--如表存在，获取游戏列表信息

FOR tab_info IN

    SELECT

        a.attname as col_name,

        pg_catalog.format_type(a.atttypid, a.atttypmod) as col_type,

        CASE WHEN

            (SELECT substring(pg_catalog.pg_get_expr(d.adbin, d.adrelid) for 128)

            FROM pg_catalog.pg_attrdef d                WHERE d.adrelid = a.attrelid AND d.adnum = a.attnum AND a.atthasdef) IS NOT NULL THEN

            \'DEFAULT \'|| (SELECT substring(pg_catalog.pg_get_expr(d.adbin, d.adrelid) for 128)

                          FROM pg_catalog.pg_attrdef d                              WHERE d.adrelid = a.attrelid AND d.adnum = a.attnum AND a.atthasdef)

        ELSE

            \'\'

        END as col_default_value,

        CASE WHEN a.attnotnull = true THEN

            \'NOT NULL\'

        ELSE

            \'NULL\'

        END as col_not_null,

        a.attnum as attnum,

        e.max_attnum as max_attnum        FROM

        pg_catalog.pg_attribute a            INNER JOIN

        (SELECT

              a.attrelid,

              max(a.attnum) as max_attnum              FROM pg_catalog.pg_attribute a              WHERE a.attnum > 0

            AND NOT www.cungun.coma.attisdropped              GROUP BY a.attrelid) e            ON a.attrelid=e.attrelid        WHERE a.attnum > 0

      AND a.attrelid=tmp_col.oid          AND NOT a.attisdropped        ORDER BY a.attnum    --拼接为ddl语句

LOOP

    IF tab_info.attnum = 1 THEN

        tab_ddl:=\'CREATE TABLE \'||tmp_col.nspname||\'.\'||tmp_col.relname||\' (\';

    ELSE

        tab_ddl:=tab_ddl||\',\';

    END IF;

    IF tab_info.attnum <= tab_info.max_attnum THEN

        tab_ddl:=tab_ddl||chr(10)||\'    \'||tab_info.col_name||\' \'||tab_info.col_type||\' \'||tab_info.col_default_value||\' \'||tab_info.col_not_null;

    END IF;

END LOOP;

  tab_ddl:=tab_ddl||\');\';

--输出结果

RETURN tab_ddl;end;$$ language plpgsql;

游戏列表用法：

select get_tab_ddl(\'table_name\');