13.2.6 INSERT Syntax

Provide a parenthesized list of comma-separated column names following the table name. In this case, a value for each named column must be provided by the VALUES list or the SELECT statement.

If you do not specify a list of column names for INSERT ... VALUES or INSERT ... SELECT, values for every column in the table must be provided by the VALUES list or the SELECT statement. If you do not know the order of the columns in the table, use DESCRIBE tbl_name to find out.

A SET clause indicates columns explicitly by name, together with the value to assign each one.

If strict SQL mode is not enabled, any column not explicitly given a value is set to its default (explicit or implicit) value. For example, if you specify a column list that does not name all the columns in the table, unnamed columns are set to their default values. Default value assignment is described in Section 11.7, “Data Type Default Values”. See also Section 1.8.3.3, “Constraints on Invalid Data”.

If strict SQL mode is enabled, an INSERT statement generates an error if it does not specify an explicit value for every column that has no default value. See Section 5.1.11, “Server SQL Modes”.

If both the column list and the VALUES list are empty, INSERT creates a row with each column set to its default value:

If strict mode is not enabled, MySQL uses the implicit default value for any column that has no explicitly defined default. If strict mode is enabled, an error occurs if any column has no default value.

Use the keyword DEFAULT to set a column explicitly to its default value. This makes it easier to write INSERT statements that assign values to all but a few columns, because it enables you to avoid writing an incomplete VALUES list that does not include a value for each column in the table. Otherwise, you must provide the list of column names corresponding to each value in the VALUES list.

If a generated column is inserted into explicitly, the only permitted value is DEFAULT. For information about generated columns, see Section 13.1.20.9, “CREATE TABLE and Generated Columns”.

In expressions, you can use DEFAULT(col_name) to produce the default value for column col_name.

Type conversion of an expression expr that provides a column value might occur if the expression data type does not match the column data type. Conversion of a given value can result in different inserted values depending on the column type. For example, inserting the string '1999.0e-2' into an INT, FLOAT, DECIMAL(10,6), or YEAR column inserts the value 1999, 19.9921, 19.992100, or 1999, respectively. The value stored in the INT and YEAR columns is 1999 because the string-to-number conversion looks only at as much of the initial part of the string as may be considered a valid integer or year. For the FLOAT and DECIMAL columns, the string-to-number conversion considers the entire string a valid numeric value.

An expression expr can refer to any column that was set earlier in a value list. For example, you can do this because the value for col2 refers to col1, which has previously been assigned:

But the following is not legal, because the value for col1 refers to col2, which is assigned after col1:

An exception occurs for columns that contain AUTO_INCREMENT values. Because AUTO_INCREMENT values are generated after other value assignments, any reference to an AUTO_INCREMENT column in the assignment returns a 0.

Inserting NULL into a column that has been declared NOT NULL. For multiple-row INSERT statements or INSERT INTO ... SELECT statements, the column is set to the implicit default value for the column data type. This is 0 for numeric types, the empty string ('') for string types, and the “zero” value for date and time types. INSERT INTO ... SELECT statements are handled the same way as multiple-row inserts because the server does not examine the result set from the SELECT to see whether it returns a single row. (For a single-row INSERT, no warning occurs when NULL is inserted into a NOT NULL column. Instead, the statement fails with an error.)

Setting a numeric column to a value that lies outside the column's range. The value is clipped to the closest endpoint of the range.

Assigning a value such as '10.34 a' to a numeric column. The trailing nonnumeric text is stripped off and the remaining numeric part is inserted. If the string value has no leading numeric part, the column is set to 0.

Inserting a string into a string column (CHAR, VARCHAR, TEXT, or BLOB) that exceeds the column's maximum length. The value is truncated to the column's maximum length.

Inserting a value into a date or time column that is illegal for the data type. The column is set to the appropriate zero value for the type.

For INSERT examples involving AUTO_INCREMET column values, see Section 3.6.9, “Using AUTO_INCREMENT”.

If INSERT inserts a row into a table that has an AUTO_INCREMENT column, you can find the value used for that column by using the LAST_INSERT_ID() SQL function or the mysql_insert_id() C API function.

If you use the LOW_PRIORITY modifier, execution of the INSERT is delayed until no other clients are reading from the table. This includes other clients that began reading while existing clients are reading, and while the INSERT LOW_PRIORITY statement is waiting. It is possible, therefore, for a client that issues an INSERT LOW_PRIORITY statement to wait for a very long time.

LOW_PRIORITY affects only storage engines that use only table-level locking (such as MyISAM, MEMORY, and MERGE).

If you specify HIGH_PRIORITY, it overrides the effect of the --low-priority-updates option if the server was started with that option. It also causes concurrent inserts not to be used. See Section 8.11.3, “Concurrent Inserts”.

HIGH_PRIORITY affects only storage engines that use only table-level locking (such as MyISAM, MEMORY, and MERGE).

If you use the IGNORE modifier, errors that occur while executing the INSERT statement are ignored. For example, without IGNORE, a row that duplicates an existing UNIQUE index or PRIMARY KEY value in the table causes a duplicate-key error and the statement is aborted. With IGNORE, the row is discarded and no error occurs. Ignored errors generate warnings instead.

IGNORE has a similar effect on inserts into partitioned tables where no partition matching a given value is found. Without IGNORE, such INSERT statements are aborted with an error. When INSERT IGNORE is used, the insert operation fails silently for rows containing the unmatched value, but inserts rows that are matched. For an example, see Section 23.2.2, “LIST Partitioning”.

Data conversions that would trigger errors abort the statement if IGNORE is not specified. With IGNORE, invalid values are adjusted to the closest values and inserted; warnings are produced but the statement does not abort. You can determine with the mysql_info() C API function how many rows were actually inserted into the table.

For more information, see Comparison of the IGNORE Keyword and Strict SQL Mode.

If you specify ON DUPLICATE KEY UPDATE, and a row is inserted that would cause a duplicate value in a UNIQUE index or PRIMARY KEY, an UPDATE of the old row occurs. The affected-rows value per row is 1 if the row is inserted as a new row, 2 if an existing row is updated, and 0 if an existing row is set to its current values. If you specify the CLIENT_FOUND_ROWS flag to the mysql_real_connect() C API function when connecting to mysqld, the affected-rows value is 1 (not 0) if an existing row is set to its current values. See Section 13.2.6.2, “INSERT ... ON DUPLICATE KEY UPDATE Syntax”.

INSERT DELAYED was deprecated in MySQL 5.6, and is scheduled for eventual removal. In MySQL 8.0, the DELAYED modifier is accepted but ignored. Use INSERT (without DELAYED) instead. See Section 13.2.6.3, “INSERT DELAYED Syntax”.