SELECT clauses

The
SELECT
 statement supports the
ALL
 and
DISTINCT
 set quantifiers. You cannot use
CASE
 and
WHEN
 expressions.
  • FROM
    TIP:
    You can use subqueries for the
    FROM
     and for the
    IN
     predicate.
    The
    FROM
     clause is required, other clauses are optional.
    The clauses must have the following order:
    FROM
    ,
    WHERE
    ,
    GROUP
    ,
    HAVING
    ,
    ORDER
    ,
    LIMIT
    .
  • JOIN
  • AS
    TIP: Aliases for tables and columns support regular and delimited identifiers.
  • WHERE
  • GROUP BY
  • ORDER BY
  • Set function, including:
    COUNT
    ,
    MAX
    ,
    MIN
    ,
    AVG
    , and
    SUM
    .
  • HAVING
  • LIMIT
    TIP:
    Use the
    LIMIT OFFSET
     variant to limit the number of records. The offset is optional and its default value is
    0
    .
    For example,
    SELECT * FROM Table1 LIMIT 1000 OFFSET 10
     returns 1000 records starting from the record number 10.

Supported functionality

Supported SELECT functionality
Expected behavior
Query to achieve the expected behavior
Retrieve all columns from a table.
SELECT * FROM Table1;
Retrieve specific columns from a table.
SELECT Column1, Column2 FROM Table1;
Use column aliases to improve readability.
SELECT Column1 AS Alias1, Column2 AS Alias2 FROM Table1;

Unsupported functionality

  • Using DISTINCT to retrieve unique values.
  • Using CASE expressions for conditional logic.

Examples

The following are examples of
SELECT
 clauses:
SELECT * FROM Table1
SELECT *, Timestamp AS T FROM Table1
SELECT Column1 FROM Table1
SELECT *, 10 FROM Table1
SELECT 10, * FROM Table1
SELECT *, 'text value' FROM Table1
SELECT COUNT(*) FROM Table1
SELECT DISTINCT Column1 FROM Table1
SELECT Variable1 AS Label, AVG(Variable1) AS Value FROM Datalogger1 AS A 
    UNION JOIN (SELECT Variable2 AS Label, AVG(Variable2) AS Value FROM Datalogger1 ORDER BY Label ASC) AS B
    ON A.Label = B.Label AND A.Value = B.Value
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