判断表是否存在方法1:

postgres if ,when及判断表是否存在的sql编写教程

SELECT  case  WHEN   a.cc =1 THEN 2 else 0 END
FROM
(
select  count(*) as cc from pg_class where relname = 'wo'    --wo is table name,pg_class是pg自带的关键字
) as a  

postgres if ,when及判断表是否存在的sql编写教程

方法2:


用if判断,但有以下条件

The IF statement is part of the default procedural language PL/pgSQL. You need to create a function or execute an ad-hoc statement with the DO command.、

exist使用要求和if一样

1 2 3 4 5 6 7 8 9 10 11 DO`$do$BEGINIF (select  count(*) cc from pg_class where relname = 'wo') = 0 --一定要加括号THEN   INSERT INTO wo VALUES (2);ELSE   INSERT INTO wo VALUES (1);END IF;END$do`$

联合使用select 和insert的方法如下

create table language_ko(Key text,XML text);
insert into Language_ko(key,xml) (select "Key " as key,'<'||"Key"||'>'||"Korean"||'</'||"Key"||'>' as xml  from "centralClient1")

标签: when, pg, postgres, select, sql, END, class, cc, wo

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