那么实际上,在这里,USE_CONCAT和NO_EXPAND成了互为"反函数"。在使用了NO_EXPAND提示后,从Oracle8之后,Oracle会使用"inlist iterator" 方式来执行SQL,这样可以用到index。 http://www.eygle.com/sql/How.to.Use.USE_CONCAT.hints.in.Oracle.htm
3 2 INDEX (UNIQUE SCAN) OF 'PK_EMP' (UNIQUE) (Cost=1 Card=14) 4 1 TABLE ACCESS (BY INDEX ROWID) OF 'EMP' (Cost=2 Card=1 Bytes=37) 5 4 INDEX (UNIQUE SCAN) OF 'PK_EMP' (UNIQUE) (Cost=1 Card=14) --使用use_concat提示以后,Oracle将in-lists条件展开为两个查询块,分别使用索引...
CONCAT and CONCAT_WS function in SQL Server Concatenate SQL Server Columns into a String with CONCAT() SQL CONCAT
String sqlUpdate = "update student set name = concat(name , 'copy')"; //3.ResultSet类,用来存放获取的结果集!! statement.executeUpdate(sqlUpdate); sql = "select * from student"; //3.ResultSet类,用来存放获取的结果集!! rs = statement.executeQuery(sql); System.out.println("---"); Syst...
I was looking for a CONCAT function in SQL Server 2008 R2. I found the link for this function. But when I use this function, it gives the following error:
"how to use CONCAT and WHERE statement in the same query","id":"message:4139588","revisionNum":1,"repliesCount":1,"author":{"__ref":"User:user:2471132"},"depth":0,"hasGivenKudo":false,"board":{"__ref":"Forum:board:SQL_Server"},"conversation":{"_...
The aggregate dimension of the data row whose GROUPING__ID is 3 is province. SQL Implementation -- SQL - 6 with group_dimension as ( select -- Dimension fields corresponding to each group gb.group_id, concat_ws(",", collect_list(case when gb.placeholder_bit = 0 then dim_col.val else...
We can use SQL SELECT Distinct to find unique references of data. For example, we have a result set that shows different rows of a table and each row consists of columns. Now sometimes we are more interested in unique patterns of the data rather than the data itself which is one of the...
sqlcmd is a command-line utility for ad hoc, interactive execution of Transact-SQL (T-SQL) statements and scripts and for automating T-SQL scripting tasks. To use sqlcmd interactively, or to build script files for sqlcmd, you should understand T-SQL. You can use sqlcmd in various ways....
3 rows in set (0.00 sec) 1. 2. 3. 4. 5. 6. 7. 8. 9. 10. 11. 12. 注意:这里用到CONCAT()函数,用来把字符串串接起来。另外,我们还用到以前学到的AS给结果列'CONCAT(f_name, " ", l_name)'起了个假名。 5.1创建数据表 命令:create ...