Gbase8s database select has order by Clause 5

Use the selection number

In the column name position , You can go to ORDER BY Clause , To quote listed in Projection Clause

The location of the items listed in the selection list of . You can also use the selection number to sort by expression .

The following example uses the selection number in a nested sort to follow the expression paid_date - order_date and customer_num row

order ：

SELECT order_num, customer_num, paid_date - order_date

FROM orders

ORDER BY 3, 2;

When passed UNION or UNION ALL Keyword connection SELECT When the sentence is , Or when there are incompatible columns in the same location

With the same name , stay ORDER BY You need to select a number in the clause .

Press Rowid Sort

You can go to ORDER BY Clause ROWID keyword . This specifies rowid Column , In the table divided into slices and with WITH

ROWIDS Clause creates a hidden column in a partitioned table .rowid Columns contain unique internal records associated with rows in the table

Number .（ However , It is recommended that you use the primary key as your access method , Instead of using rowid Column .）

If the table you are selecting from is one without rowid A partitioned table of columns , be ORDER BY Clause cannot specify rowid

Column .

When you are in ORDER BY Clause ROWID when , You don't need to be in Projection Clause includes ROWID The key

word .

To get information about rowid Values and how to use them in list expressions rowid Column for further information , see also WITH

ROWIDS Options and Use Rowid.

with DECLARE Of ORDER BY Clause

stay GBase 8s ESQL/C in , You may not use the with FOR UPDATE Clause DECLARE Statement to compare a cursor with no

ORDER BY Clause SELECT Statement .

stay ORDER BY Set index on column

When you are in SELECT The statement includes ORDER BY When clause , You can do this by ORDER BY Clause specifies one or more columns

Create indexes on columns to improve query performance . The database server uses your ORDER BY The index set on the column to be most efficient

To sort the query results . To learn more about how to create and ORDER BY The information of the index corresponding to the column of the clause ,

see also Use ASC and DESC Sort order options .