Mysql Modify Column Not Null

mysql tutorial to modify the table / field to add / delete table index create table test (blob_col blob, index (blob_col (10))); In mysql 5.1, myisam and innodb table prefix can reach 1000 bytes long. Note that the prefix limit should be measured in bytes, while the prefix length in the create table statement is interpreted as the number of characters. Must be considered when specifying the prefix length for columns that use multi-byte character sets. ...

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 _...

One, the mail system installs 1, the package installs Postfix+courier-imap+cyrus-sasl+pam_mysql+mysql this kind of installation method is simple and easy, installs under the Debian more convenient: # apt Install Courier-pop postfix-mysql postfix-tls courier-authdaemon\courier-authmysql libpam-mysql l ...

SQL used to manipulate the database is generally divided into two kinds, one is the query, which is what we call the SELECT statement, the other is to update the statement, also known as data manipulation statements. The implication is to modify the data. There are 3 statements in the standard SQL, which are INSERT, UPDATE, and DELETE. There is another REPLACE statement in MySQL, so this article uses MySQL as a background to discuss how to make updates in SQL. First, INSERT and REPLACE I ...

To use Hadoop, data consolidation is critical and hbase is widely used. In general, you need to transfer data from existing types of databases or data files to HBase for different scenario patterns. The common approach is to use the Put method in the HBase API, to use the HBase Bulk Load tool, and to use a custom mapreduce job. The book "HBase Administration Cookbook" has a detailed description of these three ways, by Imp ...

Recently wanted to do a DataGrid function through PHP things, so that you can directly modify the contents of the database table, without the development of [new data page], [edit page], so looking for the Internet to find something similar A, open source, have paid, but basically are based on MySQL. Due to the need to connect to Oracle personally from the secondary development and page style phpMyDataGrid is still quite good. This article first introduced the use of MySQL-based methods, and then briefly introduce the Oracle connection (based on ...

PHP Tutorial Imports Excel into the MySQL Tutorial database tutorial, using Excelparser class Excelparser {private $_data=array (0, ");     Private $_excel_handle; Private $_excel=array ();

Fourteen make PHP beginners a big headache Summary Today for everyone to give PHP beginners a headache big summary, the following 14 questions hope for PHP beginners to help. 1, the page can not be passed variables get, post, session Automatic global variables in the latest php version is turned off, so to get over the variables from the previous page to use $ _GET ['foo'], $ _ POST [ 'foo'], $ _ SESSION ['foo']. Of course it can be ...