convert json to mysql table

(' name ');A unique index was created for the Name column, and the name of the index is name_unique_index.To add a normal index:ALTER TABLE person ADD INDEX birthday_index (' birthday ');To delete an index:ALTER TABLE person DROP INDEX Birthday_index;ALTER TABLE person DROP INDEX Name_unique_index;Disabling non-unique indexesALTER

------------------------------------------------------ + 1 row in set (0.00 sec) We can see that the column subject or big5 encoding is not changed to utf8 encoding. We can use 2. alter table tablename convert to character set utf8; TO modify the column encoding. Mysql> show create table mybig5;

| Eucjpms_japanese_ci | 3 |+----------+-----------------------------+---------------------+--------+ View the MySQL character set command above for Windows Linux.Four. Modifying the character set of tables and fieldsModify Databasemysql> ALTER DATABASE name character set UTF8;Modify TableALTER TABLE name convert to character set GBK;modifying fieldsALTER

. Left JOIN and Straight_join forced table read Order can help the Join optimizer work faster because fewer table exchanges are checked. Note that this means that if you perform the following type of query, MySQL performs a full scan of B because the left join forces it to read before D: SELECT *From A,b left join C on (C.key=a.key) left join D on (D.key=a.key)W

value is updated to 2) Table1 Field id (without auto_increment), title (varchar (200), content (varchar (500), date (DATETIME) 300 records. each data table has about MB. each update requires about 2-3 K Records. If you directly copy the data, the MYSQL connection time is too long, resulting in MYSQL Performance decline table1 will be similar to the locking

clause to rename a column. To do this, specify the old and new column names and the current type of the column. For example, to rename an INTEGER column from a to B, you can do this: MySQL> alter table t1 CHANGE a B INTEGER; If you want to CHANGE the column type rather than the name, even if they are the same, the CHANGE syntax still requires two column names. For example:

We can directly use alter to modify the character set of the mysql table. However, we should pay attention to the inclusion relationship between codes when modifying the data set. It is best to back up the data table to avoid garbled characters. The correct statement for changing the table character set is:Alter

Modify the partition field bitsCN.com online in the MySQL partition table partition. MySQL partition table partition online partition field modification The company is using partition online. the partition field of a table is incorrect and needs to be rebuilt. it turns out

Some times you may need to bulk convert the MySQL table engine, as follows for PHP operations /** * Bulk conversion MySQL table engine */ Error_reporting (E_all); Database Connection Configuration $host = ' localhost '; $username = ' root '; $passwd = '; $database = ' Test '

reference aliases: mysql> SELECT col_name FROM tbl_name AS a WHERE. col_name = 1 or. col_name = 2; if it is difficult to use uppercase or lowercase letters in the memory database and table name, we recommend that you use the same conventions, such as creating databases and tables with lowercase letters. Another way to avoid this problem is to start mysqld with The-O lower_case_table_names = 1 parameter. By

a and A to reference aliases: Mysql> SELECT col_name FROM tbl_name AS a WHERE a. col_name = 1 or a. col_name = 2; If it is difficult to use uppercase or lowercase letters in the memory database and table name, we recommend that you use the same conventions. for example, you can always use lowercase letters to create databases and tables. Another way to avoid this problem is to start mysqld with The-O lower

DROP TABLE IF EXISTS [Temp_table_name];Create temporary table [Temp_table_name] Select Col1,col2,... from [table_name];ALTER TABLE [Temp_table_name] Add unique idx_col1 (col1);Through the above operation, the warning problem occurs many times. Through the query and tracking debugging source code, there are the following clues and processing methods:The location o

char(64) declare @b2 char(255) select @i=1 while @i begin select @a1= ‘aaa’ + convert(varchar(64),@i) select @b2= ‘bbbbbbbbbbbbbbbbbbbbbbb’ + convert(varchar(64),@i) insert into AAA values(@a1,@b2,@i) select @i=@i+1 end end Oracle test Stored Procedure CREATE OR REPLACE PROCEDURE sp_AAA(a int) AS i int; a1 varchar2(64); b2 varchar2(255);

), ADD CONSTRAINT fk_stu_tea_tid FOREIGN KEY (tid) REFERENCES teacher (TID) ); At this point, each record in the Stu_tea table is to illustrate the relationship between student and teacher tables. For example, records in the Stu_tea table: SID is 1001,tid to 2001, this indicates that the student with number 1001 has a teacher numbered 2001 Sid Tid 101 201 */* The student with number 101 has a teacher number

) Select,sort optimization measures are relatively small.6) suitable for OLTP applications.Non-standardized features:1) Store a lot of data in a single table, data redundancy.2) Update data overhead is large, updating a property may update many tables, many records.3) It is possible to lose data when deleting data.4) Select,order has a lot of optimization options.5) suitable for DSS applications.Both standardization and non-standardization have their

MySQL data type and table structureDb,database-Databases: Data collections that are organized and placed into memory according to a data model.Dnms,database Management System-Database management system: a large-scale service software used to manipulate and manage databases.Dbs,database System-Database system: Db+dbms, which refers to a computer system with database and integrated database management softwar

The correct statement to change the table character set is:ALTER TABLE XXX convert to character set UTF8;Rather than take for granted:ALTER TABLE XXX default CharSet UTF8; The character set is converted from GBK to UTF8,Increases the space occupied by the field and may change the type of the field:For example, text is

number of inserts are completed. In this way, the READ lock is allowed after a certain number of WRITE locks. · If you have questions about INSERT and SELECT, switch to the new MyISAM table because they support concurrent SELECT and INSERT. Www.2cto.com. If you INSERT or delete a table in hybrid mode, insert delayed will be of great help. · If you have a problem using the SELECT and DELETE statements in co