SQL -- Process Multi-condition query and SQL page query on the page
Two methods are used to process multi-condition queries in the past. The first method is to determine the fields to be filled in the condition, and then determine whether the input parameter is null. If it is null, use 1 = 1 to replace this condition
1.in when the query condition is ListSelectId="getmultimomentscommentscounts"Resulttype="int">SelectMoment_comment_count fromTbl_moment_commentcountwhereMidinchforeachitem="Item"index="Index"collection="List"open="("Separator=","Close=")">#{item}foreach> Select>.1 if the type of the parameter is list, then when used, the collection property must be specified as a list
select id= "findbyidsmap" resultmap="Baseresultmap">
Select
include refi
My Date
The first date format we get is this: 2009-2-12 or 2009-3-3 or 2009-10-12, we can do this by combining SQL statements: (three examples)
The code is as follows
Copy Code
@1select * from user where birthday> ' 2009-2-3 ' and birthday
This allows us to find all user information that includes 2009-2-3 and is greater than 2009-2-3.
@2 If that's how we mix it.
The code is as follows
Copy Code
Query and delete SQL statements of Repeated Records and query SQL statements of records
SQL statement for querying and deleting duplicate records1. Search for redundant duplicate records in the Table. duplicate records are determined based on a single field (peopleId ).Selec
SQL Server quickly generates SQL addition, deletion, modification, and query statements, and SQL addition and DeletionAre you still coding to generate SQL statements? Are you still speechless for SQL statements that are sloppy? Ar
results of multiple SELECT statements together, in which case it is necessary to combine the results of several SELECT statements, for example, to query all the employee information of company A and Company B, and then merge the results of the two queries together. The Union and UNION ALL keywords are used for the merge operation. Format: SELECT statement 1 UNION | UNION All SELECT statement 2 UNION | UNION All ............ Example:
Use pt-query-digest to find the SQL statement that is not suitable, pt-query-digestsql
Overview of pt-query-digest1.
Indexes can be executed more quickly, but there must be unreasonable indexes. If you want to find those indexes that are not very suitable and optimize them before they become problems, you can use the p
First, simple query
SQL (structured query Language) Structured Query language is a database query and programming language for accessing data and querying, updating, and managing relational database systems. ANSI (American National Standards Institute) claims that
SQLServer how to use the T-SQL command to query a database in which tables, convenient table operations, need friends can refer to the next
SQLServer how to use the T-SQL command to query a database in which tables, convenient table operations, need friends can refer to the next
1.
1. query all tables in SQL:
Select TABLE_NAME FROM database name. INFORMATION_SCHEMA.TABLES Where TABLE_TYPE = 'base table' after execution, you can see the names of all tables created by yourself in the database.
2. query all tables and columns in SQL:
Select dbo. sysobjects. name as Table_name, dbo. syscolumns.
Next: T-SQL Dynamic Query (1)--IntroductionObjective:In the development of features, we often encounter scenarios such as the following: The application has a query function that allows the user to select the desired condition in many query conditions. This is also the focus of this series.But sometimes you may find th
SQL query statement "3": Multi-Table query (also called connection query, which is a connection query based on two tables)If a query needs to operate on multiple tables, it is called a connection
1. Query all tables in sql:
Select table_name from database name. Information_schema. Tables Where table_type= ' BASE table ' is executed, you can see the names of all the tables in the database that belong to you
2. Query all tables and columns in sql:Select Dbo.sysobjects.name as TABLE_NAME, dbo.syscolumns.name as column_name from Dbo.syscolumns INNER JOIN
Connection Query
You can use the join operator to query multiple tables. Connection is the main feature of the relational database model and a symbol that distinguishes it from other types of database management systems.
In the relational database management system, the relationship between data does not have to be determined when a table is created, and all information about an object is often stored in a
1. query all tables in SQL:Select TABLE_NAME FROM database name. INFORMATION_SCHEMA.TABLES Where TABLE_TYPE = 'base table' after execution, you can see the names of all tables created by yourself in the database.2. query all tables and columns in SQL:Select dbo. sysobjects. name as Table_name, dbo. syscolumns. name AS Column_name FROM dbo. syscolumns inner join dbo. sysobjects ON dbo. syscolumns. id = dbo.
Label:Next: T-SQL Dynamic Query (3)--Static SQLObjective: There's a lot of talk about dynamic queries, and this article describes some of the ways to use dynamic SQL to solve dynamic queries.Why use Dynamic sql: in many projects, dynamic SQL is widely used and even misused,
Grade> = 90
-- Use "logical expression" as the query condition ......
/*
Logical expressions in SQL:
Not: non
And: corresponds
Or: or
*/
Select * from Student
-- Query the student table for a 19-year-old male student.
Select * from Student where Sage = 19 and Ssex = 'male'
-- Query the student whose age is 19 or 20 in
Advanced query technology is mainly related to multiple tables linked query technology, embedded SELECT statement subquery technology, the combination of multiple queries combined technology.
1. Connection Query
You need to retrieve data from two or more tables at the same time. A link allows you to retrieve data from two tables or more than two tables at the s
Tags: SQL statement electronic win style SPAN different statement column DTS --Connect remote SQL or insert data with OPENROWSET
--if only temporary access, you can directly use OPENROWSET
--Query Example
Select * from OpenRowset('SQLOLEDB'
,'SQL Server name';'User name';'Password', database name. dbo. Table name)
The content source of this page is from Internet, which doesn't represent Alibaba Cloud's opinion;
products and services mentioned on that page don't have any relationship with Alibaba Cloud. If the
content of the page makes you feel confusing, please write us an email, we will handle the problem
within 5 days after receiving your email.
If you find any instances of plagiarism from the community, please send an email to:
info-contact@alibabacloud.com
and provide relevant evidence. A staff member will contact you within 5 working days.