PostgreSQL查看或生成表的建表语句

连接pg的jdbc的url格式：jdbc:postgresql://ip:port/dbname

查看指定库的所有表和视图信息

--法一：查询当前登录url所在可下public的
SELECT a.oid,
       a.relname AS name,
       b.description AS comment
FROM pg_class a
       LEFT OUTER JOIN pg_description b ON b.objsubid=0 AND a.oid = b.objoid
WHERE a.relnamespace = (SELECT oid FROM pg_namespace WHERE nspname='public') --用户表一般存储在public模式下
  AND a.relkind='r'
ORDER BY a.relname;

--表信息
select * from pg_tables where schemaname='public' and tableowner='db_name';
--视图的定义
select definition from pg_views where viewname='xxxx' and viewowner='xxxxx';

查看表的建表信息

--法一
SELECT a.attnum,
       a.attname AS field,
       t.typname AS type,
       a.attlen AS length,
       a.atttypmod AS lengthvar,
       a.attnotnull AS notnull,
       b.description AS comment
FROM pg_class c,
     pg_attribute a
       LEFT OUTER JOIN pg_description b ON a.attrelid=b.objoid AND a.attnum = b.objsubid,
     pg_type t
WHERE c.relname = 'xxxxxx'
  and a.attnum > 0
  and a.attrelid = c.oid
  and a.atttypid = t.oid
ORDER BY a.attnum;

--法二
select
  col.table_schema,
  col.table_name,
  col.ordinal_position,
  col.column_name,
  col.data_type,
  col.character_maximum_length,
  col.numeric_precision,
  col.numeric_scale,
  col.is_nullable,
  col.column_default,
  des.description
from
  information_schema.columns col left join pg_description des on
        col.table_name::regclass = des.objoid
      and col.ordinal_position = des.objsubid
where
    table_schema = 'public'
  and table_name = 'xxxxxx'
order by
  ordinal_position;

生成表的建表语句

CREATE OR REPLACE FUNCTION generate_create_table_statement(p_table_name varchar)
  RETURNS text AS
$BODY$
DECLARE
    v_table_ddl   text;
    column_record record;
BEGIN
    FOR column_record IN 
        SELECT 
            b.nspname as schema_name,
            b.relname as table_name,
            a.attname as column_name,
            pg_catalog.format_type(a.atttypid, a.atttypmod) as column_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 column_default_value,
            CASE WHEN a.attnotnull = true THEN 
                'NOT NULL'
            ELSE
                'NULL'
            END as column_not_null,
            a.attnum as attnum,
            e.max_attnum as max_attnum
        FROM 
            pg_catalog.pg_attribute a
            INNER JOIN 
             (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 ~ ('^('||p_table_name||')$')
                AND pg_catalog.pg_table_is_visible(c.oid)
              ORDER BY 2, 3) b
            ON a.attrelid = b.oid
            INNER JOIN 
             (SELECT 
                  a.attrelid,
                  max(a.attnum) as max_attnum
              FROM pg_catalog.pg_attribute a
              WHERE a.attnum > 0 
                AND NOT a.attisdropped
              GROUP BY a.attrelid) e
            ON a.attrelid=e.attrelid
        WHERE a.attnum > 0 
          AND NOT a.attisdropped
        ORDER BY a.attnum
    LOOP
        IF column_record.attnum = 1 THEN
            v_table_ddl:='CREATE TABLE '||column_record.schema_name||'.'||column_record.table_name||' (';
        ELSE
            v_table_ddl:=v_table_ddl||',';
        END IF;
 
        IF column_record.attnum <= column_record.max_attnum THEN
            v_table_ddl:=v_table_ddl||chr(10)||
                     '    '||column_record.column_name||' '||column_record.column_type||' '||column_record.column_default_value||' '||column_record.column_not_null;
        END IF;
    END LOOP;
 
    v_table_ddl:=v_table_ddl||');';
    RETURN v_table_ddl;
END;
$BODY$
  LANGUAGE 'plpgsql' COST 100.0 SECURITY INVOKER;