SELECT Statements
A SELECT statement can consist of the following basic clauses.
- SELECT
- INTO
- FROM
- JOIN
- WHERE
- GROUP BY
- HAVING
- UNION
- ORDER BY
- LIMIT
SELECT Syntax
The following syntax diagram outlines the syntax supported by the SQL engine of the driver:
SELECT {
[ TOP <numeric_literal> | DISTINCT ]
{
*
| {
<expression> [ [ AS ] <column_reference> ]
| { <table_name> | <correlation_name> } .*
} [ , ... ]
}
[ INTO csv:// [ filename= ] <file_path> [ ;delimiter=tab ] ]
{
FROM <table_reference> [ [ AS ] <identifier> ]
} [ , ... ]
[ [
INNER | { { LEFT | RIGHT | FULL } [ OUTER ] }
] JOIN <table_reference> [ ON <search_condition> ] [ [ AS ] <identifier> ]
] [ ... ]
[ WHERE <search_condition> ]
[ GROUP BY <column_reference> [ , ... ]
[ HAVING <search_condition> ]
[ UNION [ ALL ] <select_statement> ]
[
ORDER BY
<column_reference> [ ASC | DESC ] [ NULLS FIRST | NULLS LAST ]
]
[
LIMIT <expression>
[
{ OFFSET | , }
<expression>
]
]
} | SCOPE_IDENTITY()
<expression> ::=
| <column_reference>
| @ <parameter>
| ?
| COUNT( * | { [ DISTINCT ] <expression> } )
| { AVG | MAX | MIN | SUM | COUNT } ( <expression> )
| NULLIF ( <expression> , <expression> )
| COALESCE ( <expression> , ... )
| CASE <expression>
WHEN { <expression> | <search_condition> } THEN { <expression> | NULL } [ ... ]
[ ELSE { <expression> | NULL } ]
END
| <literal>
| <sql_function>
<search_condition> ::=
{
<expression> { = | > | < | >= | <= | <> | != | LIKE | NOT LIKE | IN | NOT IN | IS NULL | IS NOT NULL | AND | OR | CONTAINS | BETWEEN } [ <expression> ]
} [ { AND | OR } ... ]
Examples
- Return all columns:
SELECT * FROM Orders
- Rename a column:
SELECT [Total] AS MY_Total FROM Orders
- Cast a column's data as a different data type:
SELECT CAST(AnnualRevenue AS VARCHAR) AS Str_AnnualRevenue FROM Orders
- Search data:
SELECT * FROM Orders WHERE ParentId = '3'
- Return the number of items matching the query criteria:
SELECT COUNT(*) AS MyCount FROM Orders
- Return the number of unique items matching the query criteria:
SELECT COUNT(DISTINCT Total) FROM Orders
- Return the unique items matching the query criteria:
SELECT DISTINCT Total FROM Orders
- Summarize data:
SELECT Total, MAX(AnnualRevenue) FROM Orders GROUP BY Total
See Aggregate Functions for details. - Retrieve data from multiple tables.
SELECT Orders.Id, Orders.Total, OrderNotes.* FROM OrderNotes n INNER JOIN Orders o ON n.OrderId = o.Id
See JOIN Queries for details. - Sort a result set in ascending order:
SELECT ParentId, Total FROM Orders ORDER BY Total ASC
- Restrict a result set to the specified number of rows:
SELECT ParentId, Total FROM Orders LIMIT 10
- Parameterize a query to pass in inputs at execution time. This enables you to create prepared statements and mitigate SQL injection attacks.
SELECT * FROM Orders WHERE ParentId = @param
Pseudo Columns
Some input-only fields are available in SELECT statements. These fields, called pseudo columns, do not
appear as regular columns in the results, yet may be specified as part of the WHERE clause. You can use pseudo columns to access additional features from WooCommerce.
SELECT * FROM Orders WHERE Pseudo = '@Pseudo'