SQL sqlite 是否支持选择中的任何类型的 IF(condition) 语句

Does sqlite support any kind of IF(condition) statement in a select

提问by Matt Peters

Does sqlite support the sql function "if" in the select statement?

sqlite是否支持select语句中的sql函数“if”？

for example

例如

select if( length( a ) > 4 , a , ' ') as b
from foo

which would return a if the length was over 4 chars long. or else it would return ' ' as b

如果长度超过 4 个字符，它将返回 a。否则它会返回 ' ' 作为 b

If it does support a condition in the select what is the syntax is should be using?

如果它确实支持 select 中的条件，则应该使用什么语法？

I have checked http://sqlite.org/lang_corefunc.htmlbut I can't see it.

我已经检查过 http://sqlite.org/lang_corefunc.html但我看不到它。

回答by user151019

See the caseexpression.

参见案例表达。

A CASE expression serves a role similar to IF-THEN-ELSE in other programming languages.

CASE 表达式的作用类似于其他编程语言中的 IF-THEN-ELSE。

For your example

对于你的例子

select case when length(a) > 4 then a else '' end as b
from foo

回答by Paul Dixon

You can use casefor that:

您可以为此使用案例：

select case when length(a)>4 then a else ' ' end from foo;