Documentation Home
MySQL 5.5 Reference Manual
Related Documentation Download this Manual
PDF (US Ltr) - 27.0Mb
PDF (A4) - 27.1Mb
PDF (RPM) - 25.4Mb
HTML Download (TGZ) - 6.3Mb
HTML Download (Zip) - 6.4Mb
HTML Download (RPM) - 5.4Mb
Man Pages (TGZ) - 159.2Kb
Man Pages (Zip) - 263.0Kb
Info (Gzip) - 2.6Mb
Info (Zip) - 2.6Mb
Excerpts from this Manual

13.2.5 INSERT Syntax

INSERT [LOW_PRIORITY | DELAYED | HIGH_PRIORITY] [IGNORE]
    [INTO] tbl_name
    [(col_name [, col_name] ...)]
    {VALUES | VALUE} (value_list) [, (value_list)] ...
    [ON DUPLICATE KEY UPDATE assignment_list]

INSERT [LOW_PRIORITY | DELAYED | HIGH_PRIORITY] [IGNORE]
    [INTO] tbl_name
    SET assignment_list
    [ON DUPLICATE KEY UPDATE assignment_list]

INSERT [LOW_PRIORITY | HIGH_PRIORITY] [IGNORE]
    [INTO] tbl_name
    [(col_name [, col_name] ...)]
    SELECT ...
    [ON DUPLICATE KEY UPDATE assignment_list]

value:
    {expr | DEFAULT}

value_list:
    value [, value] ...

assignment:
    col_name = value

assignment_list:
    assignment [, assignment] ...

INSERT inserts new rows into an existing table. The INSERT ... VALUES and INSERT ... SET forms of the statement insert rows based on explicitly specified values. The INSERT ... SELECT form inserts rows selected from another table or tables. INSERT with an ON DUPLICATE KEY UPDATE clause enables existing rows to be updated if a row to be inserted would cause a duplicate value in a UNIQUE index or PRIMARY KEY.

For additional information about INSERT ... SELECT and INSERT ... ON DUPLICATE KEY UPDATE, see Section 13.2.5.1, “INSERT ... SELECT Syntax”, and Section 13.2.5.2, “INSERT ... ON DUPLICATE KEY UPDATE Syntax”.

Inserting into a table requires the INSERT privilege for the table. If the ON DUPLICATE KEY UPDATE clause is used and a duplicate key causes an UPDATE to be performed instead, the statement requires the UPDATE privilege for the columns to be updated. For columns that are read but not modified you need only the SELECT privilege (such as for a column referenced only on the right hand side of an col_name=expr assignment in an ON DUPLICATE KEY UPDATE clause).

You can use REPLACE instead of INSERT to overwrite old rows. REPLACE is the counterpart to INSERT IGNORE in the treatment of new rows that contain unique key values that duplicate old rows: The new rows replace the old rows rather than being discarded. See Section 13.2.8, “REPLACE Syntax”.

tbl_name is the table into which rows should be inserted. Specify the columns for which the statement provides values as follows:

  • 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.

Column values can be given in several ways:

  • 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 11.6, “Data Type Default Values”. See also Section 1.7.3.3, “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 5.1.10, “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:

    INSERT INTO tbl_name () VALUES();

    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.

  • 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:

    INSERT INTO tbl_name (col1,col2) VALUES(15,col1*2);

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

    INSERT INTO tbl_name (col1,col2) VALUES(col2*2,15);

    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.

INSERT statements that use VALUES syntax can insert multiple rows. To do this, include multiple lists of comma-separated column values, with lists enclosed within parentheses and separated by commas. Example:

INSERT INTO tbl_name (a,b,c) VALUES(1,2,3),(4,5,6),(7,8,9);

Each values list must contain exactly as many values as are to be inserted per row. The following statement is invalid because it contains one list of nine values, rather than three lists of three values each:

INSERT INTO tbl_name (a,b,c) VALUES(1,2,3,4,5,6,7,8,9);

VALUE is a synonym for VALUES in this context. Neither implies anything about the number of values lists, nor about the number of values per list. Either may be used whether there is a single values list or multiple lists, and regardless of the number of values per list.

The affected-rows value for an INSERT can be obtained using the ROW_COUNT() SQL function or the mysql_affected_rows() C API function. See Section 12.15, “Information Functions”, and Section 23.8.7.1, “mysql_affected_rows()”.

If you use an INSERT ... VALUES statement with multiple value lists or INSERT ... SELECT, the statement returns an information string in this format:

Records: N1 Duplicates: N2 Warnings: N3

If you are using the C API, the information string can be obtained by invoking the mysql_info() function. See Section 23.8.7.35, “mysql_info()”.

Records indicates the number of rows processed by the statement. (This is not necessarily the number of rows actually inserted because Duplicates can be nonzero.) Duplicates indicates the number of rows that could not be inserted because they would duplicate some existing unique index value. Warnings indicates the number of attempts to insert column values that were problematic in some way. Warnings can occur under any of the following conditions:

  • 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.

    Note

    These two functions do not always behave identically. The behavior of INSERT statements with respect to AUTO_INCREMENT columns is discussed further in Section 12.15, “Information Functions”, and Section 23.8.7.37, “mysql_insert_id()”.

The INSERT statement supports the following modifiers:

  • If you use the DELAYED modifier, the server puts the row or rows to be inserted into a buffer, and the client issuing the INSERT DELAYED statement can then continue immediately. If the table is in use, the server holds the rows. When the table is free, the server begins inserting rows, checking periodically to see whether there are any new read requests for the table. If there are, the delayed row queue is suspended until the table becomes free again. See Section 13.2.5.3, “INSERT DELAYED Syntax”.

    DELAYED is ignored with INSERT ... SELECT or INSERT ... ON DUPLICATE KEY UPDATE.

    DELAYED is also disregarded for an INSERT that uses functions accessing tables or triggers, or that is called from a function or a trigger.

  • 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 (or even forever) in a read-heavy environment. (This is in contrast to INSERT DELAYED, which lets the client continue at once.)

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

    Note

    LOW_PRIORITY should normally not be used with MyISAM tables because doing so disables concurrent inserts. See Section 8.11.3, “Concurrent Inserts”.

  • 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 may generate warnings instead, although duplicate-key errors do not.

    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 19.2.2, “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.

  • 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 13.2.5.2, “INSERT ... ON DUPLICATE KEY UPDATE Syntax”.

An INSERT statement affecting a partitioned table using a storage engine such as MyISAM that employs table-level locks locks all partitions of the table. This does not occur with tables using storage engines such as InnoDB that employ row-level locking. This issue is resolved in MySQL 5.6. For more information, see Section 19.5.4, “Partitioning and Table-Level Locking”.