cmgi field

1. Add a field:ALTER TABLE tablename add NEW_FIELD_ID type NOT null default ' 0 ';Cases:ALTER TABLE Mmanapp_mmanmedia add appid_id integer NOT null default 372;Add primary key: alter table tabelname add new_field_id type default 0 not nullauto_increment,add primary key (new_field_id);add foreign key:Add a FOREIGN KEY constraint on a field that already existsALTER TABLE yourtablename ADD [CONSTRAINT symbol] FOREIGN KEY [id] (index_col_name, ...) REFER

1. Add a field ALTER TABLE user add COLUMN new1 VARCHAR (x) DEFAULT NULL; 　　 Add a field that defaults to null ALTER TABLE user add COLUMN new2 VARCHAR (a) not NULL; 　　　　　　　　　　　　　　 Add a field, default cannot be empty//2. Delete a field ALTER TABLE user DROP COLUMN new2; 　　　　　　　　　　 Delete a

Tags: Eva TGA bpm ACM JMH CGO Lua VTP BSDBefore, when I was doing statistics, I needed a field to show the order quantity and order amount for a month, and to combine it into a single field in parentheses. The result of the statistic is probably this, first we create some simulation data ---create order form---CREATE TABLE Omsorder (UidintIdentity1,1) primary key, Organizename varchar ( -) notNULL, OrderCou

The simple Syntax of MySQL is commonly used, but it is not easy to remember. Of course, these SQL syntaxes are basically common in various databases. Listed below: 1. Add a field Alter table user add column new1 varchar (20) default null; // Add a field, empty by defaultAlter table user add column new2 varchar (20) not null; // Add a field, which cannot be blan

Obtain the table field name (SORT ): SELECT. name as field name FROM syscolumns a inner join sysobjects d on. id = d. id and d. xtype = 'U' and d. name Expected table field name: Select name from syscolumns Where ID = OBJECT_ID ('table name ') Field names can be obtained horizontally: Select * from Table NameDeclare

Label:MySQL's simple syntax, often used, is not easy to remember. Of course, these SQL syntaxes are basically common in each database. listed below: 1. Add a field ALTER TABLE user add column new1 VARCHAR default null;//Add a field, default is empty ALTER TABLE user add column New2 VARCHAR (not NULL); Add a field, default cannot be empty www.2cto.com 2. D

// Primary key alter table tabelname add new_field_id int(5) unsigned default 0 not null auto_increment ,add primary key (new_field_id); // Delete a column alter table t2 drop column c; // Rename a column alter table t1 change a b integer; // Change the column type alter table t1 change b b bigint not null;alter table infos change list list tinyint not null default '0'; // Rename the table alter table t1 rename t2; Add Index Mysql> alter table tablename change depno int (5) not null; mysql> alte

0. PrefaceUnderstanding the JVM virtual machine principle is a necessary step for every Java programmer to practice. But because there are a lot of things in the JVM virtual machine to tell the relatively broad, in the current exposure to the JVM virtual machine principle of the tutorial or blog, the vast majority of the text-based description, it is difficult to give people a visual perception, after reading the feeling is still confused.Feeling the above, I intend to learn from the process of

Field attributeThe previous section describes how to create a table containing different types of fields. In this section, you will learn how to use the three attributes of a field. These attributes allow you to control null values, default values, and identity values. Allow and disable null valuesMost fields can accept null values ). When a field accepts a null

The field is similar to the previous construction method and behavior method; Package javainvokefiled;Import Java.lang.reflect.Field; /*** Reflection Get Field* @author Administrator**/Class filed{public String name;private int age;private int number;public String password; Public Filed () {}} public class Invokefiled {/*** Get the field method and the previous

1. Add a field The code is as follows Copy Code Add a field, the default is emptyALTER TABLE user add COLUMN new1 VARCHAR DEFAULT NULL;Add a field, default cannot be emptyALTER TABLE user add COLUMN new2 VARCHAR is not NULL; 2. How to add the field in bulkMethod OneYou can use tra

Tags: os SP data BS Database SQL nbsp Table method1.DataTable DT; Assuming the field is name, DT has saved the datadt.rows[0]["name"] = = System.DBNull.Value; Determines whether the name field of the first row of data is empty2.DataTable DT; Assuming the field is name, DT has saved the datadt.rows[0]["Name"]. ToString () = = ""; Determines whether the name

' table_name ' DROP PRIMARY key;*/-----------------------------------------------------------CREATE Create an index-----------------------------------------------------------create unique index index_name on ' table_name ' (' column '); --Creating a full-text index create FULLTEXT index_name on ' table_name ' (' column '); --Create INDEX index_name on ' table_name ' (' column ') for normal indexes; --Create INDEX index_name on ' table_name ' (' column1 ', ' column2 ', ' column3 '). --Drop index

--oracle See all of the user's table names, table comments, field names, field comments, empty, field type SELECT DISTINCT table_column.*, table_nallable. Data_type, table_nallable. NULLABLE from (SELECT DISTINCT Utc.table_name table_name, utc.comments table_comments, Ucc.column_name column_name, ucc.comments column_comments from User_tab _

--oracle See all the user's table names, table gaze, field name, field gaze, is empty, field type SELECT DISTINCT table_column.*, table_nallable. Data_type, table_nallable. NULLABLE from (SELECT DISTINCT Utc.table_name table_name, utc.comments table_comments, Ucc.column_name column_name, ucc.comments column_comments from User_tab _comments

Tags: lock data and site refactoring attribute data structure block strong wrapperIn the reconstruction of the site, the data structure is usually modified, so add, delete, add the MySQL table field is unavoidable, and sometimes for convenience, but also increase the modification of the table or field comments, the same field attributes to the same. These actions

Label:In the reconstruction of the site, the data structure is usually modified, so add, delete, add the MySQL table field is unavoidable, and sometimes for convenience, but also increase the modification of the table or field comments, the same field attributes to the same. These actions can be done in phpMyAdmin or other MySQL management tools, but we sometimes

Oracle displays the user's table names, Table Comments, field names, field comments, whether it is empty, field type, and oracle fields. -- Oracle: view all the table names, Table Comments, field names, field comments of the user, whether the table is empty, and select disti

In mysql, we only need to use alter to modify the data table fields. Below I will introduce how to modify the table field name, field length, and field type in mysql, for more information, see. Let's take a look at common methods. The simple Syntax of MySql is commonly used, but it is not easy to remember. Of course, these SQL syntaxes are basically common in var

The check box can be used to select multiple items. when entering some forms, the browser sometimes needs to select multiple items (such as interests and hobbies). the check box usually exists at the same time, to facilitate value transfer, the name can be defined as an array: inputtype... the check box can be used to select multiple items. when entering some forms, the viewer sometimes needs to select multiple items (such as interests and hobbies) Check boxes usually exist at the same time. to