postgresql 根据查询结果为变量设置值（PL/pgSQL 风格）
声明：本页面是StackOverFlow热门问题的中英对照翻译，遵循CC BY-SA 4.0协议，如果您需要使用它，必须同样遵循CC BY-SA许可，注明原文地址和作者信息，同时你必须将它归于原作者（不是我）：StackOverFlow
原文地址: http://stackoverflow.com/questions/17187873/
Warning: these are provided under cc-by-sa 4.0 license. You are free to use/share it, But you must attribute it to the original authors (not me):
StackOverFlow
Set a value to a variable based on the results of a query (in PL/pgSQL style)
提问by Oto Shavadze
What I need to do is set a value to a variable using the EXECUTINGquery.
我需要做的是使用EXECUTING查询为变量设置一个值。
In pure SQL style, I could do something like the following:
在纯 SQL 样式中，我可以执行以下操作：
// here declaring function and etc...
DECLARE cnt INTEGER;
EXECUTE 'SELECT COUNT(*) FROM t' INTO cnt;
How to achieve the same functionality in the form of a PL/pgSQL function? What is the correct syntax for the following pseudo-code? (The following is obviously the wrong syntax)
如何以 PL/pgSQL 函数的形式实现相同的功能？以下伪代码的正确语法是什么？（以下显然是错误的语法）
cnt := EXECUTE ( 'SELECT COUNT(*) FROM t' ) ;
回答by Kurt Burns
I think what you are looking for is:
我认为你正在寻找的是：
cnt := COUNT(*) FROM t;
回答by Roberto
you can use SELECT INTO
你可以使用 SELECT INTO
DECLARE cnt INTEGER;
SELECT INTO cnt count(*) FROM t;
回答by Roberto
Not sure what you mean by "plpgsql style". The syntax you showed is perfectly OK, as shown in documentation.
不确定“plpgsql 风格”是什么意思。您展示的语法完全没问题，如文档中所示。
