Can Prepared Statements Handle Dynamic Column Names in SQL Queries?

Using Prepared Statements for Dynamic Column Names

When working with database queries, a common dilemma arises when trying to specify dynamic column names. This article explores the possibility of passing variable column names through prepared statements, particularly in MySQL using Java.

Challenge Statement

As the user attempts to execute the prepared statement, the column names are passed in as a string:

String columnNames = "d,e,f";
String query = "SELECT a,b,c,? FROM " + name + " WHERE d=?";
stmt = conn.prepareStatement(query);
stmt.setString(1, columnNames);
stmt.setString(2, "x");

However, the resulting SQL statement displays the column names as part of the literal string:

SELECT a,b,c,'d,e,f' FROM some_table WHERE d='x'

The desired output, however, is to have the column names as separate columns:

SELECT a,b,c,d,e,f FROM some_table WHERE d='x'

Solution Discussion

It's crucial to note that this practice indicates a flawed database design. Ideally, users should not be aware of the column names. A better solution would be to create an explicit column in the database to store the "column names" instead.

Unfortunately, setting column names as PreparedStatement values is not possible. Prepared statements can only be used to set column values.

If the use of variable column names is unavoidable, sanitizing the input and manually constructing the SQL string is necessary. This involves quoting the individual column names and escaping quotes within the column names using String#replace().

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