SQL 以表达式开头（使用“LIKE”）
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SQL startswith (using `LIKE`) on an expression
提问by HoverHell
What's an appropriate way to do startswith(expression)in SQL?
startswith(expression)在 SQL 中做什么的合适方法是什么？
I can do it with LIKE ((expression) || '%'), but it doesn't look very nice to me.
我可以用 来做LIKE ((expression) || '%')，但对我来说它看起来不太好。
Full query is in form:
完整的查询格式为：
SELECT …, (SELECT COUNT(*)
FROM post AS child
WHERE child.path LIKE (post.path || '%')
AND child.depth >= post.depth)
FROM post WHERE …
I suppose it is preferable to use LIKEbecause of DB indexing for this case.
我想最好使用LIKE这种情况下的数据库索引。
回答by Scott Anderson
Just use LIKE 'input%'. I.E:
只需使用LIKE 'input%'. IE：
WHERE child.path LIKE post.path + '%'
(I assume this is for SQL Server, though this syntax probably works elsewhere)
（我假设这是针对 SQL Server 的，尽管此语法可能适用于其他地方）
回答by Tom Anderson
In standard SQL, you can also say:
在标准 SQL 中，您还可以说：
where position(post.path in child.path) = 0
I don't know if your RDBMS supports that. PostgreSQL does.
我不知道你的 RDBMS 是否支持。PostgreSQL 可以。
回答by Antonio García
You can use
您可以使用
where DATE LIKE '[(SELECT STR(YEAR(GETDATE())-1))]%'
where DATE LIKE '[(SELECT STR(YEAR(GETDATE())-1))]%'
WHERE child.path LIKE '[(SELECT STR(YEAR(GETDATE())-1))]%' (post.path || '%')
WHERE child.path LIKE '[(SELECT STR(YEAR(GETDATE())-1))]%' (post.path || '%')
