Error 1065 – SQLSTATE: HY000 (ER_EMPTY_QUERY) “Query was empty” in MySQL

by

When you encounter the MySQL Error 1065, it means that you’ve attempted to execute an empty query – that is, there’s no actual SQL statement to be run. This can happen in various scenarios, such as a programming mistake where a query string remains uninitialized or is cleared before being sent to the database, or even a logic error where the conditions for building a dynamic query result in an empty string.

Diagnosing the Error

To diagnose this error, you need to:

  1. Check your application code where the query is being prepared. Ensure that the SQL statement is not an empty string.
  2. If you’re using a script file, make sure there are no accidental semicolons that could terminate the statement prematurely, resulting in an empty query being sent.
  3. If your query is dynamically generated, add debugging statements to output the final query string before it is executed. This will help you verify whether the query is indeed empty or not.

Fixing the Error

Here are some examples and sample code to help you fix the Error 1065:

Example 1: Static Query

If your query is static (not dynamically generated), it should be straightforward:

INSERT INTO my_table (column1, column2) VALUES ('value1', 'value2');

Ensure that the above query string is not empty when it’s being executed.

Example 2: Dynamic Query Generation

When generating queries dynamically, ensure the logic correctly concatenates parts of the query:

$query = "INSERT INTO my_table (column1, column2) VALUES (";
$query .= "'value1', 'value2'";
$query .= ");";

if ($query != ";") {
    mysqli_query($connection, $query);
} else {
    echo "Error: Query was empty";
}

In the above PHP code, we’re building the query string in parts and checking if the final query is just a semicolon (which would indicate an empty query).

Example 3: Conditional Query Execution

Sometimes you might only want to execute a query if certain conditions are met:

query = "DELETE FROM my_table WHERE id = %s" % (record_id) if record_id is not None else ""
if query:
    cursor.execute(query)
else:
    print("Error: Query was empty")

In this Python example, we’re only setting the query variable if record_id is not None. Then we check if query is not an empty string before executing it.

Example 4: Handling User Input

If your query includes user input, make sure the input is validated and leads to a valid query:

let userId = getUserInput(); // Function to get user input
let query = userId ? `SELECT * FROM users WHERE id = ${userId}` : "";

if (query) {
    database.execute(query);
} else {
    console.error("Error: Query was empty");
}

In this JavaScript example, we only construct the query if userId is truthy, which helps prevent an empty query.

Remember, always validate and sanitize user inputs to prevent SQL injection attacks.

Conclusion

By carefully checking the code where your SQL query is formed and ensuring that the query string is not empty before execution, you can avoid the Error 1065. Implementing proper checks and debugging can help you quickly diagnose and fix issues related to empty queries in MySQL.

Leave a Comment