PreparedStatement `executeQuery()`: Why Use It Without a SQL String Parameter?

PreparedStatement Syntax Error: A Deeper Dive

You've encountered an error message related to PreparedStatements. Examining your code, specifically the selectSql1 query and the select1 method, reveals a subtle issue.

The problem lies in the usage of the PreparedStatement's executeQuery method. Your select1 method currently attempts to call:

return this.stmt.executeQuery(sql);

where sql is the SQL query itself. This is not the correct way to use an executeQuery method on a PreparedStatement.

Solution

The fix is simply updating that line to:

return this.stmt.executeQuery();

By removing the sql parameter from the executeQuery method, you ensure that the PreparedStatement's internal query is executed instead of the raw SQL string. PreparedStatements provide placeholder parameters denoted by question marks (?) in the SQL query, which are then bound to specific values like randNum.

Therefore, the correct executeQuery call in this context is without any parameters, allowing the PreparedStatement to execute its internal query, which has already been bound with parameter values.

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