how to tune sql query

to 90 points SELECT * from SC Student where grade>=90 --use "logical expression" as a query condition ... /* Logical Expressions in SQL: Not: Non- And: With Or: OR */ SELECT * FROM Student --Check the student's table for male students aged 19 years SELECT * from Student where Sage = Ssex = ' Male ' --Check the student's table for students ages 19 or 20 years old SELECT * from Student where sag

What is parameterized query? A simple way to understand parameterized queries is to think of it as just a T-SQL query that accepts parameters that control what the query returns. By using different parameters, a parameterized query returns different results. To obtain a para

Query for common methods:@Override Public List operator) { = "Select Mat_no_, sum (amount_) as Spent_amount_ from Dm_mat_month_plan where Mat_type_ =? and Dept_code_ =? and Year_ =? and Process_status_ in (1, 2) GROUP by Mat_no_ "; return dmjdbctemplate.queryforlist (SQL, Mat_type_, Dept_code_, year_); }A query that can be empty method:@Ove

, integer field. Example: Userage int float, floating-point data is approximate. Example: Userresults float, the approximate numeric data type used to represent floating-point numeric data. datetime, Date type. Example: Createdatetime datetime Bit, Boolean type. Can be set to True is male, false is schoolgirl If the content is very much, indeterminate length (such as article), can be used: nvarchar (max)6. Save the table:* If you want to modify the table, save it, and then refre

This article introduces parameterized query. I will discuss how SQL Server optimizer attempts to parameterize a query and how you can create your own parameterized query if the query can be parameterized. This article introduces parameterized

From: http://www.itqun.net/content-detail/104196.html Set statistics profile on Set statistics Io on Set statistics time on The more CPU and IO resources a query requires, the slower the query speed. Therefore, another way to describe the query performance tuning task is, the query command should be rewri

Http://www.cnblogs.com/dubing/archive/2011/12/09/2278090.htmlRecently the company has come to a very tiger DBA 10几 years of experience here is called Cai Teacher. Let us share the precious wealth that Cai Lao has brought to us, with the consent of our Chua. Welcome other DBAs to shoot bricks Directory1. What is the execution plan? The execution plan is dependent on what information.2, unified SQL statement to reduce parsing overhead3. Reduce the

Directory1. What is the execution plan? The execution plan is dependent on what information.2, unified SQL statement to reduce parsing overhead3. Reduce the nesting of SQL statements4. Staging intermediate results using temporary table5. The OLTP system SQL statement must take a binding variable6. The spy problem of the bound variable of the tilted field7. Begin

The more CPU and IO resources a query requires, the slower the query speed. Therefore, another way to describe the query performance tuning task is, the query command should be rewritten in a way that uses less CPU and IO resources. If the query can be completed in this way,

I. MySql Query Cache 1. Query Cache MySQL Query Cache is used to Cache the SELECT statement we execute and the result set of this statement. The specific technical details of MySql in implementing Query Cache are similar to the typical KV storage, it is to map the SELECT statement and the

condition in Statement 7 after the on clause.Select O. ID, O. order_number, O. customer_id, C. ID, C. NameFrom orders o left Outer Join MERs C on C. ID = O. customer_id and O. order_number The query results of statement 7 and statement 8 are obviously different, and the results displayed in Statement 8 are hard to understand. Therefore, when writing a join query, we recommend that you only follow the join