How Can I Safely Use Wildcards with Prepared Statements in SQL for Efficient Searching?

Using Wildcards in Prepared Statements for Search Functionality

When implementing a search feature using a keyword as the search parameter, it becomes necessary to utilize the LIKE keyword in SQL. However, integrating LIKE with prepared statements can be a bit tricky.

In the provided example:

PreparedStatement pstmt = con.prepareStatement(
      "SELECT * FROM analysis WHERE notes like ?");
pstmt.setString(1, notes);

The placeholder (?) in the SQL string represents the parameter that will be set with the LIKE keyword. In this case, the keyword% should be appended to the value assigned to the placeholder parameter.

Solution:

To use LIKE with prepared statements, the wildcard ('%') should be set directly in the value itself, not in the SQL string. This can be done by appending the wildcard to the value when setting the parameter:

pstmt.setString(1, notes + "%");

If a prefix match is required, the wildcard should be placed at the beginning of the value:

pstmt.setString(1, "%" + notes);

For a global match, thewildcard should be placed on both ends of the value:

pstmt.setString(1, "%" + notes + "%");

It is important to note that special characters in the value, such as %, _, [, and !, need to be escaped to avoid conflicts with their use as wildcards in the LIKE clause. The example provided in the response adequately addresses this issue by replacing these characters with escape sequences before setting the parameter.

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