FireDAC Components for Dataflex

Build 20.0.7587

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 component:

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 Accounts
  2. Rename a column:
    SELECT [Name] AS MY_Name FROM Accounts
  3. Cast a column's data as a different data type:
    SELECT CAST(AnnualRevenue AS VARCHAR) AS Str_AnnualRevenue FROM Accounts
  4. Search data:
    SELECT * FROM Accounts WHERE Name <> 'MyAccount';
  5. Return the number of items matching the query criteria:
    SELECT COUNT(*) AS MyCount FROM Accounts 
  6. Return the number of unique items matching the query criteria:
    SELECT COUNT(DISTINCT Name) FROM Accounts 
  7. Return the unique items matching the query criteria:
    SELECT DISTINCT Name FROM Accounts 
  8. Summarize data:
    SELECT Name, MAX(AnnualRevenue) FROM Accounts GROUP BY Name
    See Aggregate Functions for details.
  9. Retrieve data from multiple tables.
    SELECT Accounts.Name, Contracts.ContractNumber FROM Accounts, Contracts WHERE Accounts.AccountId=Contracts._AccountId_Value
    See JOIN Queries for details.
  10. Sort a result set in ascending order:
    SELECT accountid, Name FROM Accounts  ORDER BY Name ASC
  11. Restrict a result set to the specified number of rows:
    SELECT accountid, Name FROM Accounts 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 Accounts WHERE Name = @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 Dataflex.

    SELECT * FROM Accounts WHERE Pseudo = '@Pseudo'
    

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Build 20.0.7587