Table of Contents 1. Specification background and purpose 2. Design specification 2.1. Database design 2.1.1. Library name 2.1.2. Table structure 2.1.3. Column data type optimization 2.1.4.
Tag: mysql
MySQL connection
MySQL connection Connect using mysql binary mode You can use MySQL binary mode to enter the mysql command prompt to connect to the MySQL database.
The following is a simple example of connec
MySQL – SQL JOIN table, 1 of which has a comma
When I search for “new1”, how to get all usernames. For example: I should get A and B as user IDs 1,2 in tblC is 1,2 and there is new for row1 1. What query should I use to get the above result?
I
Mysql build environment
Forget the root password;
①Close the service:
sudo service mysql stop;
②Safe mode + authentication-free startup service
sudo /usr/local/mysql/ bin/mysqld_safe –skip-grant-tables
MySQL advanced query
1. The grouping field is merged from multiple lines into one line.
mysql> select user_id,tag_id from yyfax_user.user_tag where user_id=‘U000412280’;
+————+———-+
| user_id | ta
How to handle null values in WHERE IN conditions in mysql
I want to include the possible values as null in the conditions of the mysql query.
This is my query: but it doesn’t show any values. Please suggest me how to write WHERE IN The condition contai
Chinese characters (Chinese) in mysql sorted in the first letters of the pinyin
Because the encoding format of the table can be set in the database, there are differences in the sorting of Chinese under different encoding formats. The following are the sorting methods under co
解决MySQL Update：You can’t specify target table for update in FROM clause
You can’t specify target in MySQL The error of table for update in FROM clause means that you cannot select some values in the same table first, and then update this table (in the same statement)
MySQL backup file. XB database backup restore
Today an old friend told me that his mysql backup file suffix .xb could not be restored, or it was restored with only tables without data, so I decided to try I did a backup and restore, and I sear
MySQL supported data type
Data types supported by mysql Integer ”’ Type tinyint: 1 byte, value range -128~127, default length 4 smallint: 2 bytes, value range -32768 ~ 32767, default length 6 mediumint: 3 bytes int: 4 byte