UnhandledPromiseRejectionWarning: Error: Column count doesn't match value count at row 1 on bulk insert with Node JS mysql2

Are you encountering an UnhandledPromiseRejectionWarning: Error: Column count doesn't match value count at row 1 error while performing a bulk insert with Node.js mysql2? Don't worry, we're here to help you troubleshoot and resolve this issue.

This error typically occurs when the number of columns specified in your SQL query doesn't match the number of values you are trying to insert. Let's dive into the possible causes and solutions.

1. Incorrect Number of Values

The most common cause of this error is an incorrect number of values in your insert statement. Ensure that you are providing the correct number of values for each column in your table.

For example, if you have a table with three columns (id, name, age), your insert statement should include three corresponding values:

INSERT INTO my_table (id, name, age) VALUES (1, 'John Doe', 25);

Make sure the number of values matches the number of columns in your table, and that the values are provided in the correct order.

2. Missing or Extra Columns

Another possible cause is missing or extra columns in your insert statement. Check if you have missed any columns or added extra columns in the statement.

For example, if your table has three columns (id, name, age), but your insert statement only provides values for two columns:

INSERT INTO my_table (id, name) VALUES (1, 'John Doe');

In this case, you need to provide a value for the missing column or remove the extra column from your insert statement.

3. Mismatched Column Order

Ensure that the order of the columns in your insert statement matches the order of the columns in your table. If the column order is different, the values will be inserted into the wrong columns, resulting in a column count mismatch error.

Double-check the column order in your insert statement and compare it with the column order in your table definition.

4. Null or Default Values

If your table has columns with default values or allows NULL values, make sure to handle them properly in your insert statement.

If a column has a default value and you don't provide a value for it in your insert statement, the default value will be used. However, if you explicitly provide a value for that column, ensure it matches the expected data type.

If a column allows NULL values and you want to insert a NULL value, make sure to use the keyword NULL instead of providing an empty value.

5. Escaping Special Characters

If your values contain special characters like quotes or backslashes, make sure to properly escape them in your insert statement.

You can use the mysql2.escape() function to escape the values before inserting them into the query.

const value = "John's value";
const escapedValue = mysql2.escape(value);
const query = `INSERT INTO my_table (name) VALUES (${escapedValue});`

This will ensure that special characters are properly handled and won't cause a column count mismatch error.

By following these steps, you should be able to resolve the UnhandledPromiseRejectionWarning: Error: Column count doesn't match value count at row 1 error in your Node.js mysql2 bulk insert. Double-check your insert statement for the correct number of values, column order, and proper handling of NULL or default values. Additionally, ensure that any special characters in your values are properly escaped.

If you are still facing issues, feel free to reach out to our technical support team for further assistance.

References