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Use GROUP_CONCAT Syntax: GROUP_CONCAT ([DISTINCT] expr [, expr...] [order by {unsigned_integer | col_name | expr} [ASC | DESC] [, col_name...] [SEPARATOR str_val]) The following shows the function. First, create a student_courses table and fill in

Differences between analyze and dbms_stats functions collect statistical information as follows: SQL code select table_name, num_rows, blocks, avg_row_len from user_tables where table_name = 'T '; www.2cto.com SQL code analyze table t compute

Introduction: Oracle DatabaseThere is no constraint. Oracle databases must comply with certain rules. As we all know, few of us work in isolation; most PL/SQL development work is carried out in a relatively large organization. But we basically work

Oracle multi-table insert all statement: SQL code create table ORDERS (CUSTOMER_ID NUMBER, SUM_ORDERS NUMBER); create table small_customers (CUSTOMER_ID NUMBER, SUM_ORDERS NUMBER ); create table medium_customers (CUSTOMER_ID NUMBER, SUM_ORDERS

Oracle may have this requirement to obtain the date after the specified working day. You want to obtain the specific date after the delay (excluding weekends and holidays) based on the start time and the number of days after the specified working

In Oracle recursive queries, we often use the Start with... Connect By clause to perform Oracle recursive queries. In general, it is used to maintain the tree structure of related tables. The following is a detailed description of the article. I

Create a MySQL stored procedure and use bitsCN.com Create and use a MySQL stored procedure 1. create a stored procedure: SQL code Create procedure proc_name (out s int) -- CREATE a stored PROCEDURE. proc_name indicates that the out parameter

Analysis on sorting of null values in mysql bitsCN.com Analysis on sorting of null values in mysql Table t_user: Name age Zhangsan 1 Lisi NULL Wangwu 2 Run the following SQL statement: SQL code Select * from t_user order by age; Name

Solve mysqlamp; quot; Accessdeniedforuser bitsCN.com Solve the problem of mysql "Access denied for user 'root' @ 'IP address '" In MYSQL, remote software is used to log on to the server, sometimes the following occurs: Access denied for user 'root'

Mysql database maintenance statement bitsCN.com Mysql database maintenance statement 1. modify the table name SQL code Alter table t1 rename to t1_back_20130502 2. export structure SQL code Mysqldump-h192.168.1.1-uroot-p1234 --

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1. Create an Oracle global temporary table. The Code is as follows: SQL code DECLAREcntint; begin -- if the temporary table exists, delete SELECTcount ( 1. Create an Oracle global temporary table. The Code is as follows: SQL code DECLARE cnt int;

Multiple table INSERT statements are divided into the following four types:① unconditional insert.② conditional Insert All.③ transpose insert.④ conditional Insert First.First create a test table:CREATE TABLE EMP ( empno Number (4), ename

How does mysql print the latest purchased product information in the array? there is a book table (stitle is the product name, and one ID can buy multiple books, for example, a user with ID 1 can buy, SQLcode field idstitletime1a, B, 2011-01-012c, d,

PHP MySQL How to get table comments $sql = "Show create table about"; $query =mysql_query ($sql); How do I write the following to get the table comments? Thank you. ------Solution-------------------- Field? The proud frog has the answer SELECT

Update Update Xxx Set Xxx Where As we all know about this writing, we found that update and delete support the update method of inner join, which is very useful for updating and deleting operations between tables. Column: SQLCode Update Tb_user

Today, we will summarize the Oracle Job Queue Manager (Job Queue), which will be convenient for future queries.There are two ways to do a scheduled task: One is: OS timing, win scheduled task, and Unix crontab.One is: database-level timing, her

Mysql removes duplicate data bitsCN.com Select can take alias, delete cannot. 1. when you use mysql to perform the delete from operation, if the FROM statement of the subquery and the update/delete object use the same table, an error will

Solve the Problem of mysql "Access denied for user 'root' @ 'IP address'". In MYSQL, remote software is used to log on to the server, sometimes the following occurs: access denied for user 'root' @ 'localhost' www.2cto.com this problem occurs mainly

Mysql database read/write splitting Data Synchronization I used two xp (one master, one slave) systems to test successfully, and I also did a test on linux systems, however, I think the problem I encountered is the same. In xp, the problem can be