Mysql Alter Table Default

ALTER alter alter the name of the table structure of the name of the table ALTER TABLE ALTER TABLE ALTER TABLE statement is used to add, modify or delete columns in the existing table. sql alter table syntax To add a column to a table, use the following syntax: alter table table_name add column_name datatype To delete a column in a table, use the following syntax: alter table table _...

If a computer manufacturer, its database holds machine and accessories product information. The table used to save the whole product information is called pc; the table used to save the parts supply information is called parts. There is a field in the pc table, used to describe the type of CPU used in this computer; there is a field in the parts table, the description of the CPU model, we can think of it as a list of all CPU models. Obviously, the CPU used by this manufacturer must be a model that exists in the supply information sheet. At this time, two tables ...

The following article is mainly about the specific method of implementing a simple and practical optimization of the MySQL database, as well as what specific steps in the actual operation are worthy of our attention. The following article describes the MySQL database is a simple practical optimization of the specific methods to achieve, including how to conduct regular table analysis and inspection, and how to properly optimize the table on a regular basis, the following is a description of the specific program, I hope in your future Learning will be helpful. 1, regular analysis table and checklist analysis table syntax is as follows: ANAL ...

Usually speaking of foreign keys, we only mention "the purpose of the foreign key is to determine the referential integrity of the data." However, what foreign keys specifically include the actions and meanings? 1, set the outer chain: (1), create a foreign key through create table: see 2 lines of code is built in the table command: create table city (... key idx_fk_country_id (country_id), constrain ...

In this lesson, we want to learn how to increase the intelligent processing capacity of the Web page. Basic functions Welcome to the third and final lesson of this tutorial. If you've learned the first and second lessons, you've mastered the basics of installing and programming MySQL and PHP. Here are some of the other functions of PHP that might be useful to you and make your development process simpler. 　　First, let's look at the document. You should know some basic concepts of the header file, right? The header file is an external file whose contents are included in the main program. ...

BINARY is not a function, is a type conversion operator, which is used to force the string after it to be a binary string, which can be understood to be case sensitive when the string is compared as follows: mysql> select binary 'ABCD' = 'abcd' COM1, 'ABCD' = 'abcd' COM2; + -------- + ----------- + | COM1 | COM2 | + -------- + - --------- + | & nbs ...

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Current Dream Dedecms v5.7 has been officially released, but in the actual use of the environment often we need to do some specific function of the implementation, such as the letter search, and so on, let us say how the function is implemented, the main method is to extract the first letter of the publication resources, stored in the datasheet, and then indexed. Dedecms based on PHP and MySQL technology development, can be used at the same time in Windows, Linux, UNIX platform, the environment needs are as follows: 1, Windows Platform: ...