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

1. Return all columns:
   

   SELECT * FROM Payments

2. Rename a column:
   

   SELECT [DeviceName] AS MY_DeviceName FROM Payments

3. Cast a column's data as a different data type:
   

   SELECT CAST(InclusiveTaxMoneyAmount AS VARCHAR) AS Str_InclusiveTaxMoneyAmount FROM Payments

4. Search data:
   

   SELECT * FROM Payments WHERE Id = 'Jq74mCczmFXk1tC10GB'

5. Return the number of items matching the query criteria:
   

   SELECT COUNT(*) AS MyCount FROM Payments 

6. Return the number of unique items matching the query criteria:
   

   SELECT COUNT(DISTINCT DeviceName) FROM Payments 

7. Return the unique items matching the query criteria:
   

   SELECT DISTINCT DeviceName FROM Payments 

8. Summarize data:
   

   SELECT DeviceName, MAX(InclusiveTaxMoneyAmount) FROM Payments GROUP BY DeviceName

   See Aggregate Functions for details.
9. Retrieve data from multiple tables.
   

   SELECT Locations.Name, Payments.NetSalesMoneyAmount FROM Locations, Payments WHERE Locations.Locationid = Payments.LocationId

   See JOIN Queries for details.
10. Sort a result set in ascending order:
    

    SELECT Id, DeviceName FROM Payments  ORDER BY DeviceName ASC

11. Restrict a result set to the specified number of rows:
    

    SELECT Id, DeviceName FROM Payments LIMIT 10 

12. Parameterize a query to pass in inputs at execution time. This enables you to create prepared statements and mitigate SQL injection attacks.
    

    SELECT * FROM Payments WHERE Id = @param

See Explicitly Caching Data for information on using the SELECT statement in offline mode.

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 Square.

    SELECT * FROM Payments WHERE Pseudo = '@Pseudo'