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INSERT Statement

The INSERT statement inserts new data into a table.

Examples

-- insert the values (1), (2), (3) into "tbl"
INSERT INTO tbl VALUES (1), (2), (3);
-- insert the result of a query into a table
INSERT INTO tbl SELECT * FROM other_tbl;
-- insert values into the "i" column, inserting the default value into other columns
INSERT INTO tbl (i) VALUES (1), (2), (3);
-- explicitly insert the default value into a column
INSERT INTO tbl (i) VALUES (1), (DEFAULT), (3);
-- assuming tbl has a primary key/unique constraint, do nothing on conflict
INSERT OR IGNORE INTO tbl (i) VALUES (1);
-- or update the table with the new values instead
INSERT OR REPLACE INTO tbl (i) VALUES (1);

Syntax

INSERT INTO inserts new rows into a table. One can insert one or more rows specified by value expressions, or zero or more rows resulting from a query.

Insert Column Order

It’s possible to provide an optional insert column order, this can either be BY POSITION (the default) or BY NAME. Each column not present in the explicit or implicit column list will be filled with a default value, either its declared default value or NULL if there is none.

If the expression for any column is not of the correct data type, automatic type conversion will be attempted.

INSERT INTO ... [BY POSITION]

The order that values are inserted into the columns of the table is determined by the order that the columns were declared in. That is, the values supplied by the VALUES clause or query are associated with the column list left-to-right. This is the default option, that can be explicitly specified using the BY POSITION option. For example:

CREATE TABLE tbl (a INTEGER, b INTEGER);
INSERT INTO tbl VALUES (5, 42);
-- specifying "BY POSITION" is optional and is equivalent to the default behavior
INSERT INTO tbl BY POSITION VALUES (5, 42);

To use a different order, column names can be provided as part of the target, for example:

CREATE TABLE tbl (a INTEGER, b INTEGER);
INSERT INTO tbl (b, a) VALUES (5, 42);
-- adding "BY POSITION" results in the same behavior
INSERT INTO tbl BY POSITION (b, a) VALUES (5, 42);

This will insert 5 into b and 42 into a.

INSERT INTO ... BY NAME

The names of the column list of the SELECT statement are matched against the column names of the table to determine the order that values should be inserted into the table, even if the order of the columns in the table differs from the order of the values in the SELECT statement. For example:

CREATE TABLE tbl (a INTEGER, b INTEGER);
INSERT INTO tbl BY NAME (SELECT 42 AS b);

This will insert 42 into b and insert NULL (or its default value) into a.

It’s important to note that when using INSERT INTO ... BY NAME, the column names specified in the SELECT statement must match the column names in the table. If a column name is misspelled or does not exist in the table, an error will occur. Columns that are missing from the SELECT statement will be filled with the default value.

ON CONFLICT Clause

An ON CONFLICT clause can be used to perform a certain action on conflicts that arise from UNIQUE or PRIMARY KEY constraints. An example for such a conflict is shown in the following example:

CREATE TABLE tbl (i INT PRIMARY KEY, j INT);
INSERT INTO tbl VALUES (1, 42);
INSERT INTO tbl VALUES (1, 84);

This raises as an error and leaves the table with a single row <i: 1, j: 42>.

Error: Constraint Error: Duplicate key "i: 1" violates primary key constraint.

There are two supported actions: DO NOTHING and DO UPDATE SET ...

DO NOTHING Clause

The DO NOTHING clause causes the error(s) to be ignored, and the values are not inserted or updated. For example:

CREATE TABLE tbl (i INT PRIMARY KEY, j INT);
INSERT INTO tbl VALUES (1, 42);
INSERT INTO tbl VALUES (1, 84) ON CONFLICT DO NOTHING;

These statements finish successfully and leaves the table with the row <i: 1, j: 42>.

Shorthand

The INSERT OR IGNORE INTO ... statement is a shorter syntax alternative to INSERT INTO ... ON CONFLICT DO NOTHING. For example, the following statements are equivalent:

INSERT OR IGNORE INTO tbl VALUES (1, 84);
INSERT INTO tbl VALUES (1, 84) ON CONFLICT DO NOTHING;

DO UPDATE Clause

The DO UPDATE clause causes the INSERT to turn into an UPDATE on the conflicting row(s) instead. The SET expressions that follow determine how these rows are updated. The expressions can use the special virtual table EXCLUDED, which contains the conflicting values for the row. Optionally you can provide an additional WHERE clause that can exclude certain rows from the update. The conflicts that don’t meet this condition are ignored instead.

Because we need a way to refer to both the to-be-inserted tuple and the existing tuple, we introduce the special EXCLUDED qualifier. When the EXCLUDED qualifier is provided, the reference refers to the to-be-inserted tuple, otherwise it refers to the existing tuple. This special qualifier can be used within the WHERE clauses and SET expressions of the ON CONFLICT clause.

An example using DO UPDATE is the following:

CREATE TABLE tbl (i INT PRIMARY KEY, j INT);
INSERT INTO tbl VALUES (1, 42);
INSERT INTO tbl VALUES (1, 84) ON CONFLICT DO UPDATE SET j = EXCLUDED.j;
-- rearranging columns and BY NAME also work:
INSERT INTO tbl (j, i) VALUES (168, 1) ON CONFLICT DO UPDATE SET j = EXCLUDED.j;
INSERT INTO tbl BY NAME (SELECT 1 AS i, 336 AS j) ON CONFLICT DO UPDATE SET j = EXCLUDED.j;

These statements finish successfully and leaves the table with a single row <i: 1, j: 84>.

Shorthand

The INSERT OR REPLACE INTO ... statement is a shorter syntax alternative to INSERT INTO ... DO UPDATE SET c1 = EXCLUDED.c1, c2 = EXCLUDED.c2, .... That is, it updates every column of the existing row to the new values of the to-be-inserted row. For example, given the following input table:

CREATE TABLE tbl (i INT PRIMARY KEY, j INT);
INSERT INTO tbl VALUES (1, 42);

These statements are equivalent:

INSERT OR REPLACE INTO tbl VALUES (1, 84);
INSERT INTO tbl VALUES (1, 84) ON CONFLICT DO UPDATE SET j = EXCLUDED.j;
INSERT INTO tbl (j, i) VALUES (84, 1) ON CONFLICT DO UPDATE SET j = EXCLUDED.j;
INSERT INTO tbl BY NAME (SELECT 84 AS j, 1 AS i) ON CONFLICT DO UPDATE SET j = EXCLUDED.j;

Defining a Conflict Target

A conflict target may be provided as ON CONFLICT (confict_target). This is a group of columns that an index or uniqueness/key constraint is defined on. If the conflict target is omitted, or PRIMARY KEY constraint(s) on the table are targeted.

Specifying a conflict target is optional unless using a DO UPDATE and there are multiple unique/primary key constraints on the table.

CREATE TABLE tbl (i INT PRIMARY KEY, j INT UNIQUE, k INT);
INSERT INTO tbl VALUES (1, 20, 300);
INSERT INTO tbl VALUES (1, 40, 700) ON CONFLICT (i) DO UPDATE SET k = 2 * EXCLUDED.k;
-- tbl will contain <1, 20, 1400>
INSERT INTO tbl VALUES (1, 20, 900) ON CONFLICT (j) DO UPDATE SET k = 5 * EXCLUDED.k;
-- tbl will contain <1, 20, 4500> 

When a conflict target is provided, you can further filter this with a WHERE clause, that should be met by all conflicts.

INSERT INTO tbl VALUES (1, 40, 700) ON CONFLICT (i) DO UPDATE SET k = 2 * EXCLUDED.k WHERE k < 100;

Multiple Tuples Conflicting on the Same Key

Having multiple tuples conflicting on the same key is not supported. For example:

CREATE TABLE tbl (i INT PRIMARY KEY, j INT);
INSERT INTO tbl VALUES (1, 42);
INSERT INTO tbl VALUES (1, 84), (1, 168) ON CONFLICT DO NOTHING;

Running this returns the following message.

Error: Invalid Input Error: ON CONFLICT DO UPDATE can not update the same row twice in the same command.
Ensure that no rows proposed for insertion within the same command have duplicate constrained values

RETURNING Clause

The RETURNING clause may be used to return the contents of the rows that were inserted. This can be useful if some columns are calculated upon insert. For example, if the table contains an automatically incrementing primary key, then the RETURNING clause will include the automatically created primary key. This is also useful in the case of generated columns.

Some or all columns can be explicitly chosen to be returned and they may optionally be renamed using aliases. Arbitrary non-aggregating expressions may also be returned instead of simply returning a column. All columns can be returned using the * expression, and columns or expressions can be returned in addition to all columns returned by the *.

For example:

CREATE TABLE t1 (i INT);
INSERT INTO t1 
    SELECT 42
    RETURNING *;
i
42

A more complex example that includes an expression in the RETURNING clause:

CREATE TABLE t2 (i INT, j INT);
INSERT INTO t2 
    SELECT 2 AS i, 3 AS j 
    RETURNING *, i * j AS i_times_j;
i j i_times_j
2 3 6

The next example shows a situation where the RETURNING clause is more helpful. First, a table is created with a primary key column. Then a sequence is created to allow for that primary key to be incremented as new rows are inserted. When we insert into the table, we do not already know the values generated by the sequence, so it is valuable to return them. For additional information, see the CREATE SEQUENCE page.

CREATE TABLE t3 (i INT PRIMARY KEY, j INT);
CREATE SEQUENCE 't3_key';
INSERT INTO t3 
    SELECT nextval('t3_key') AS i, 42 AS j 
    UNION ALL
    SELECT nextval('t3_key') AS i, 43 AS j
    RETURNING *;
i j
1 42
2 43
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Last modified: 2024-02-27