Essential ADO.NET

B.4. Wildcard Characters

Both the * and % can be used interchangeably for wildcards in a LIKE comparison. If the string in a LIKE clause contains a * or %, those characters should be escaped in brackets ([ ]). If a bracket is in the clause, the bracket characters should be escaped in brackets (e.g., [[ ] or [ ]]). A wildcard is allowed at the beginning and end of a pattern, or at the end of a pattern, or at the beginning of a pattern. For example:

"ItemName LIKE '*product*'"
"ItemName LIKE '*product'"
"ItemName LIKE 'product*'"

Wildcards are not allowed in the middle of a string. For example, 'te*xt' is not allowed.