Categories:: Table functions

TO_QUERY¶

Returns a result set based on SQL text and an optional set of arguments that are passed to the SQL text if it is parameterized. The function compiles the SQL text as the definition of a subquery in the FROM clause. When writing an application or a stored procedure, you can call this function to construct a SQL statement.

Note

This function can include user input in query statements, which has potential security risks, such as SQL injection. If inputs to the function come from external sources, make sure they are validated. For more information, see SQL injection.

See also:: Constructing SQL at runtime

Syntax¶

TO_QUERY( SQL => '<string>' [ , <arg> => '<value>' [, <arg> => '<value>' ...] ] )

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Arguments¶

Required

SQL => 'string': String representation of the subquery.

Optional

arg => 'value': Bind variables passed to the SQL string.

Returns¶

Returns the result set produced by the execution of the specified SQL text or NULL. If any argument is NULL, the function returns NULL without reporting any error.

Usage notes¶

All arguments must be one of the following:
- Constant strings.
- SQL variables or Snowflake Scripting variables that resolve to strings.
If you need to convert a string passed in an argument to a different data type, you can use a conversion function in the SQL string to convert the string to another data type.
The set of columns defining the result set is derived from the SELECT list of the compiled SQL statement.
The function is valid only in the FROM clause of a SQL statement.

Examples¶

Create a table and insert data into it.

CREATE OR REPLACE TABLE to_query_example (
  deptno NUMBER(2),
  dname  VARCHAR(14),
  loc    VARCHAR(13))
AS SELECT
  column1,
  column2,
  column3
FROM
  VALUES
    (10, 'ACCOUNTING', 'NEW YORK'),
    (20, 'RESEARCH',   'DALLAS'  ),
    (30, 'SALES',      'CHICAGO' ),
    (40, 'OPERATIONS', 'BOSTON'  );

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The examples use the data in this table.

Using TO_QUERY in SQL statements¶

First, set a session variable (SQL variable) for the table name:

SET table_name = 'to_query_example';

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The examples use the session variable and IDENTIFIER() to identify the table.

Using IDENTIFIER() to identify database objects is a best practice because can it can make code more reusable and help to prevent SQL injection risks.

The following example uses the TO_QUERY function to return all of the data in the to_query_example table:

SELECT * FROM TABLE(TO_QUERY('SELECT * FROM IDENTIFIER($table_name)'));

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+--------+------------+----------+
| DEPTNO | DNAME      | LOC      |
|--------+------------+----------|
|     10 | ACCOUNTING | NEW YORK |
|     20 | RESEARCH   | DALLAS   |
|     30 | SALES      | CHICAGO  |
|     40 | OPERATIONS | BOSTON   |
+--------+------------+----------+

The following example uses the TO_QUERY function to return all of the values in the deptno column of the to_query_example table:

SELECT deptno FROM TABLE(TO_QUERY('SELECT * FROM IDENTIFIER($table_name)'));

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+--------+
| DEPTNO |
|--------|
|     10 |
|     20 |
|     30 |
|     40 |
+--------+

The following example uses the TO_QUERY function to pass an argument to a SQL statement so that it returns the row where deptno equals 10 in the to_query_example table:

SELECT * FROM TABLE(
  TO_QUERY(
    'SELECT * FROM IDENTIFIER($table_name)
    WHERE deptno = TO_NUMBER(:dno)', dno => '10'
    )
  );

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+--------+------------+----------+
| DEPTNO | DNAME      | LOC      |
|--------+------------+----------|
|     10 | ACCOUNTING | NEW YORK |
+--------+------------+----------+

The following example is the same as the previous example, but it uses a session variable to pass the deptno value to the TO_QUERY function:

SET dept = '10';

SELECT * FROM TABLE(
  TO_QUERY(
    'SELECT * FROM IDENTIFIER($table_name)
    WHERE deptno = TO_NUMBER(:dno)', dno => $dept
    )
  );

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+--------+------------+----------+
| DEPTNO | DNAME      | LOC      |
|--------+------------+----------|
|     10 | ACCOUNTING | NEW YORK |
+--------+------------+----------+

The following example uses the TO_QUERY function to pass two arguments to a SQL statement so that it returns the rows where deptno equals 10 or dname equals SALES in the to_query_example table:

SELECT * FROM TABLE(
  TO_QUERY(
    'SELECT * FROM IDENTIFIER($table_name)
    WHERE deptno = TO_NUMBER(:dno) OR dname = :dnm',
    dno => '10', dnm => 'SALES'
    )
  );

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+--------+------------+----------+
| DEPTNO | DNAME      | LOC      |
|--------+------------+----------|
|     10 | ACCOUNTING | NEW YORK |
|     30 | SALES      | CHICAGO  |
+--------+------------+----------+

Using TO_QUERY in stored procedures¶

The following example uses the TO_QUERY function in a stored procedure:

CREATE OR REPLACE PROCEDURE get_num_results_tq(query VARCHAR)
RETURNS TABLE ()
LANGUAGE SQL
AS
DECLARE
  res RESULTSET DEFAULT (SELECT COUNT(*) FROM TABLE(TO_QUERY(:query)));
BEGIN
  RETURN TABLE(res);
END;

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Note: If you are using SnowSQL, the Classic Console, or the execute_stream or execute_string method in Python Connector code, use this example instead (see Using Snowflake Scripting in SnowSQL, the Classic Console, and Python Connector):

CREATE OR REPLACE PROCEDURE get_num_results_tq(query VARCHAR)
RETURNS TABLE ()
LANGUAGE SQL
AS
$$
DECLARE
  res RESULTSET DEFAULT (SELECT COUNT(*) FROM TABLE(TO_QUERY(:query)));
BEGIN
  RETURN TABLE(res);
END;
$$
;

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Call the stored procedure:

CALL get_num_results_tq('SELECT * FROM to_query_example');

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+----------+
| COUNT(*) |
|----------|
|        4 |
+----------+

CALL get_num_results_tq('SELECT * FROM to_query_example WHERE deptno = 20');

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+----------+
| COUNT(*) |
|----------|
|        1 |
+----------+

The following example uses the TO_QUERY function in a stored procedure with a bind variable:

CREATE OR REPLACE PROCEDURE get_results_tqbnd(dno VARCHAR)
RETURNS TABLE ()
LANGUAGE SQL
AS
DECLARE
  res RESULTSET DEFAULT (SELECT * FROM TABLE(
    TO_QUERY(
      'SELECT * FROM to_query_example
      WHERE deptno = TO_NUMBER(:dnoval)', dnoval => :dno
    )
  ));
BEGIN
  RETURN TABLE(res);
END;

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CREATE OR REPLACE PROCEDURE get_results_tqbnd(dno VARCHAR)
RETURNS TABLE ()
LANGUAGE SQL
AS
$$
DECLARE
  res RESULTSET DEFAULT (SELECT * FROM TABLE(
    TO_QUERY(
      'SELECT * FROM to_query_example
      WHERE deptno = TO_NUMBER(:dnoval)', dnoval => :dno
    )
  ));
BEGIN
  RETURN TABLE(res);
END;
$$
;

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Call the stored procedure:

CALL get_results_tqbnd('40');

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+--------+------------+--------+
| DEPTNO | DNAME      | LOC    |
|--------+------------+--------|
|     40 | OPERATIONS | BOSTON |
+--------+------------+--------+

Call the stored procedure using a session variable:

SET dept = '20';

CALL get_results_tqbnd($dept);

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+--------+----------+--------+
| DEPTNO | DNAME    | LOC    |
|--------+----------+--------|
|     20 | RESEARCH | DALLAS |
+--------+----------+--------+