w9 statement

First, if syntaxif then -- SQL statements; Else -- SQL statements; End if;Second, if usedelimiter $$--Create statementCreate TriggerMy_tri afterInsert onOrders forEach rowbegin --get inventory of items in table Inv to variable @inv SelectInv fromGoodswhereId=new.g_id into @inv; --Compare inventory Adequacy if @inv New.g_number Then --insufficient inventory, violent error Insert intoXxxValues(XXX); End if; UpdateGoodsSetInv=Inv-New.g_numberwhereId=new.g_id;End$ $de

One: Executes the SQL statement, returning the number of rows affected In MySQL, if there is no effect, then the number of rows returned is-1, SQL Server has not been tested Usingnew Mydbcontext ()) { ctx. Database.executesqlcommand ("UPDATE person SET Name = ' Michael ' WHERE PersonID = 1");}Two: database.sqlqueryThis is exactly the ienumerableThis is the Execute SQL statement that returns the list of t

Some differences between the INSERTINTOSELECT statement and the SELECTINTOFROM statement are described. For more information, see the following description and conditions. Some differences between the insert into select statement and the select into from statement are described. For more information, see the following

SQL statement optimization principle and SQL statement optimization. SQL statement optimization principle: optimize SQL statements to process more than one million data to improve query speed: 1. avoid using the where clause as much as possible! Or operator. Otherwise, the engine will discard the SQL statement optimiza

Common SQL statement optimization skills (1) and SQL statement optimization skillsTo improve the efficiency of SQL statement execution, the most common method is to create an index and avoid full table scan. We will organize some common SQL optimization techniques to avoid full table scanning. A simple optimization may increase your SQL Execution efficiency by se

SQL statement optimization introduction and SQL statement Optimization 1. To optimize the query, try to avoid full table scanning. First, consider creating an index on the columns involved in where and order. 2. Try to avoid null value determination on the field in the where clause. When creating a table, NULL is the default value, but not null should be used in most cases, or a special value, such as 0, -1

With statement Executes a series of statements on an object. With objectstatementsEnd With Parameters Object The required part. Can be either an object name or a function that returns a value to an object. Statements The required part. One or more commands that will be executed on object . Description The WITH statement can be used to execute a series of statements on the specified object, but it does not

SQL UNION operatorThe UNION operator is used to combine the result set of two or more SELECT statements.Note that the SELECT statement inside the UNION must have the same number of columns. The column must also have a similar data type. Also, the order of the columns in each SELECT statement must be the same.SQL UNION SyntaxSELECT column_name (s) from Table_name1unionselect column_name (s) from table_name2N

SQL statement join Table query and SQL statement join query Answers to questions about SQL statement join Table query 1. Create two databases: Database A (table a) and database B (table B ). 2. allocate the same account permissions to the two databases. 3. Use the following statement during query: The Code is as foll

A for loop is the most complex loop structure in PHP. Its behavior is similar to that in C. In PHP, the number of times the same code set is executed The meaning of for in php A for loop is the most complex loop structure in PHP. Its behavior is similar to that of C language. In PHP, the number of times the same code set is executed A for loop is just a little more code and is added to it in a loop. The common tasks involved in a loop are:Set the initial values of some counter variables.Check t

PHP fails to execute the SQL statement, but the current problem that the same statement can be executed in MYSQL is that some tables in the same database can be queried, and some tables cannot be queried. However, these statements can be normally executed in mysql ------ solution ------------------ check in one case, LZ can be combined into an SQL statement on th

"A project of Php+mysql" There is a user, username is admin, password is admin. The query statements are: $sql="select * from table_project where a_username='{$username}' and a_password='{$password}';"; Then query: $res=mysql_query($sql);……省略 Because of preventing SQL injection, I wanted to escape before the SQL statement query, so I escaped with Addslashes to the $sql statement, but it went wrong. $sql=ad

ExecuteGlobal statement Execute multiple statements specified in the global namespace of the script. ExecuteGlobal statement StatementA parameter is a string expression that contains one or more executable statements. InStatementParameters can contain multiple statements and are separated by colons.Description In VBScript,X = yThere are two ways to explain. The first method is to assign a valueYAssignedX.

Label:The person who writes the program often needs to analyze whether the SQL statement that has been written has been optimized, and how fast the server responds, this time it needs to use the statistics state value of SQL to view it. by setting Statistics we can view the system situation when executing SQL. The options are Profile,io, time. Introduced as follows: SET STATISTICS profile on: Displays the time, in milliseconds, that is required to par

Property Let statement In the Class block, declare names, parameters, and code, which form the body of the property procedure for the assignment (set). [Public | Private] Property Let name ( [arglist,] value)[statement][Exit Property] [statement]End Property Parameters Public Indicates that the property Let procedure can be accessed by all other procedures in

1. Replace spaces in the field In SQL, you can use the replace function to replace certain characters in a field. The syntax is as follows: Syntax Replace (original-string, search-string, replace-string) Parameters If a parameter is null, this function returns NULL. The string to be searched by original-string. Can be of any length. The string to be searched and replaced by replace-string. The length of the string cannot exceed 255 bytes. If search-string is a null string, the original s

In PD, double-click a table and view its preview label. Then, the create statement of a table is displayed as follows: Copy codeThe Code is as follows: create table Company_Info ( Company_ID NVARCHAR2 (50) not null, Area_ID NVARCHAR2 (50 ), Mem_ID NVARCHAR2 (50 ), Level_Id NVARCHAR2 (50 ), Name NVARCHAR2 (50) not null, Capital NVARCHAR2 (50 ), Unit_Property NUMBER (2) not null, Economical mics_type NUMBER (2) not null, Man_Scale NUMBER (10, 0 ), Licen

Rem statement Contains the explanatory comments in the program. RemComment Or 'Comment CommentThe parameter is the annotation text to be included. InRemKeyword andCommentThere should be a space between them.Description As shown in the "Syntax" section, you can use single quotes (').RemKeyword. IfRemKeywords and statements must be separated by semicolons in the same line. However, if you use single quotes, you do not need to use a semicolon betwe

Const statement The Declaration is used to replace the constant of the text value. [Public | private]ConstConstname = expression Parameters Public Optional. This keyword is used to declare constants that can be used for all processes in all scripts at the script level. It cannot be used in the process. Private Optional. This keyword is used to declare constants that can only be used in the script where the declaration is located. It cannot b

SQL statement | description of connector usage, SQL statementI. | role | Indicates splicing, such as 'A' | 'B' is equivalent to 'AB'Ii. | example: Generate select statements in batches Select 'select * from' | tname | ';' from tab t where t. tname like't _ P _ % '; For example: Then you can copy these select statements to the document !!Iii. Instances | It is useful for many people who don't know. Let's take an instance for example: How to di