Gbase8s database select has order by Clause 3

Press CASE Expression sort

ORDER BY Clauses can include CASE Expression to specify the sort key .

In the following example , surface tab_case The column of a_col by INT type . Counter table tab_case Queries for include Projection

Columns in the list a_col And aggregate expressions SUM(a_col), And pass a_col Group the results by the value of .ORDER BY Clause

Specify two sort keys ：

Keep up with the ORDER BY After the keyword CASE expression

• AVG(a_col) Aggregate expression ：

CREATE TABLE tab_case(a_col INT, b_col VARCHAR(32));

SELECT a_col, SUM(a_col)

FROM tab_case

GROUP BY a_col

ORDER BY CASE

WHEN a_col IS NULL

THEN 1

ELSE 0 END ASC,

AVG(a_col);

Here it is ,ASC The keyword explicitly puts CASE The result of the expression is identified as an ascending sort key . By default ,AVG(a_col)

The sort key also specifies ascending sort .

In the following similar example , Based on the same tab_case The query on the table , the second CASE The expression returns or 1 perhaps 0

As returned AVG(a_col) Sort key value of aggregate value .

SELECT a_col, SUM(a_col)

FROM tab_case GROUP BY a_col

ORDER BY CASE

WHEN a_col IS NULL

THEN 1

ELSE 0 END ASC,

AVG(a_col),

CASE

WHEN AVG(a_col) IS NULL

THEN 1

ELSE 0 END;