SQL Like与C＃包含差异

Question

I have following SQL in C#,

var str= QueryExecutor.Query<string>("SELECT SomeColumn from Somtable WHERE SomeColumn LIKE '%abc_def%'", new { }, CommandType.Text).FirstOrDefault();
            if (str.Contains("abc_def"))
            {

            }

Now I get the big string but str.Contains("abc_def") returns false. The column is NVARCHAR(MAX). Why contains and LIKE differ?

Answer 1

You are probably missing that _ is a wildcard for SQL LIKE that matches exactly one character.

So, LIKE '%abc_def%' can match any character between the two:

abc1def
abcZdef
abc&def
abc_def

To match an underscore in SQL Server using LIKE , you can use one of the following:

SomeColumn LIKE '%abc[_]def%'             -- use a character class
SomeColumn LIKE '%abc$_def%' ESCAPE '$'   -- use an escape character

Or, you can use charindex() :

CHARINDEX('abc_def', SomeColumn) > 0