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 xBase adapter:

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> 
    ]
  ] 
}

  <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 } [ <expression> ]
    } [ { AND | OR } ... ]

Examples

1. Return all columns:
   

   SELECT * FROM Orders

2. Rename a column:
   

   SELECT "ShipCity" AS MY_ShipCity FROM Orders

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

   SELECT CAST(Freight AS VARCHAR) AS Str_Freight FROM Orders

4. Search data:
   

   SELECT * FROM Orders WHERE ShipCountry = 'USA'

5. The xBase APIs support the following operators in the WHERE clause: =, >, <, >=, <=, <>, !=, LIKE, NOT LIKE, IN, NOT IN, IS NULL, IS NOT NULL, AND, OR, CONTAINS.
   

   SELECT * FROM Orders WHERE ShipCountry = 'USA';

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

   SELECT COUNT(*) AS MyCount FROM Orders 

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

   SELECT COUNT(DISTINCT ShipCity) FROM Orders 

8. Return the unique items matching the query criteria:
   

   SELECT DISTINCT ShipCity FROM Orders 

9. Sort a result set in ascending order:
   

   SELECT ShipName, ShipCity FROM Orders  ORDER BY ShipCity ASC

Aggregate Functions

For SELECT examples using aggregate functions, see Aggregate Functions.

JOIN Queries

See JOIN Queries for SELECT query examples using JOINs.

Date Literal Functions

Date Literal Functions contains SELECT examples with date literal functions.

Window Functions

See Window Functions for SELECT examples containing window functions.

Table-Valued Functions

See Table-Valued Functions for SELECT examples with table-valued functions.