order by desc

tbl_direct_pos_201506 table has 1.9 million data, DDL:CREATE TABLE ' tbl_direct_pos_201506 ' (' Acq_ins_code ' char () not NULL DEFAULT ' COMMENT ' agency code ', ' Trace_num ' char (6) N OT null default ' COMMENT ' tracking number ', '

SELECT * FROM table where yz= ' 1 ' ORDER BY btcount Desc This writes output is incorrect, Btcount This field is very short, generally =0 or = 1, maximum no more than =8 When the amount of data is large, you cannot press the Btcount value of

The tbl_direct_pos_201506 table has 1.9 million data. Ddl:CREATE TABLE ' tbl_direct_pos_201506 ' (' Acq_ins_code ' char () not NULL DEFAULT ' COMMENT ' agency code ', ' Trace_num ' char (6) N OT null default ' COMMENT ' tracking number ', '

Note: Use BTREE to comindex ASC/DESC of each field to optimize order by query efficiency. btreeascThe tbl_direct_pos_201506 table has 1.9 million data, DDL: Create table 'tbl _ direct_pos_201506 '('acq _ ins_code' char (13) not null default

Using Reverse indexes to Improve the Performance of order by desc using reverse indexes (index desc) can greatly improve the performance of SQL statements with order by desc clauses. I. Scenario 1. Table Name: test_t, with a field name: object_id2,

ORDER BY descending desc, ascending ASC by age descending Select *from Student ORDER BY age DESCAscending by age Select *from Student ORDER BY age ASCRank function rank () in descending order of use age, if the sort field is the same, rank

Over cannot be used alone, with analytic functions: Rank (), Dense_rank (), Row_number (), and so on.Its parameters: Over (partition by columnname1 ORDER by Columnname2)Meaning: Group by the field specified by Columname1, or by the value of field

Using the reverse index (index DESC), you can significantly increase the performance of SQL statements with an ORDER BY DESC clause. Another way is to create a reverse index, such as:CREATE INDEX T_IDX on table_name (time DESC);This creation, the

using the reverse index (index DESC), you can significantly increase the performance of SQL statements with an ORDER BY DESC clause. first, the scene 1, table name: test_t, there is a field named object_id 2, total data quantity: 580000 line,

The workaround is to add a sorted field to the order by ID Desc, which can improve the speed a lot. The sorted fields vary by query such as table Copy Code code as follows: CREATE TABLE [dbo]. [Cmpp_sendcentre] ( [ID] [int] IDENTITY (1,