sql nested query example

1. SQL INSERT statement gets automatically generated increment ID value Copy Code code as follows: Insert into Table1 (name,des,num) VALUES (' LTP ', ' thisisbest ', 10); SELECT @ @identity as ' Id ' 2. Implementation is 1 or 0 want to show as male or female Copy Code code as follows: Select name,sex= (Case Sex when ' 1 ' Then ' man ' when ' 0 ' then ' female ') from TableName 3.

cursor next row of data into @AccountNo--make variable get The account number of the current cursor-specified row-----------an outer cursor, ORDER by Accountno while (@ @FETCH_STATUS =0) BEGIN set @TempTime =0 set @A Vgtime=0--average recharge time for each person set @AddTimes = 0--Each person recharge the initial set @upConsumeTime = ' 2017-11-09 00:00:00.000 ' DE CLARE consumetime_cursor Cursor for--Declare deal time--recharge record query SELECT

/* When multiple stored procedures are called in a large SQL statement and multiple stored procedures are called in the called stored procedure, after multiple nested calls, if you need to roll back the entire transaction if the primary key is repeated or the business logic is not met, you can use the following mode for processing. You can also directly count data without raiserror. If an error occurs after

[Zhuantang learning notes] basic SQL query statements (single-Table query and multi-Table query)SQLQueryBasic1. Single Table query It is also called projection. Basic query statement Structure Select column from table * Not all ot

partial database backup and file backup. The new restore statement allows you to use full or partial database backup and record file backup for restoration. These replace the dump and load statements in earlier versions of SQL Server. For a complete list of new statements and options for SQL Server 7.0 and SQL Server 2000, see the topic "new and enhanced functio

1. Simple Query　　A simple Transact-SQL query only includes the select list, from clause, and where clause. They indicate the queried columns, the queried tables or views, and the search conditions.　　For example, the following statement queries the nick name and email fields in the testtable table with the name "Zhang S

." If the search uses an index, it is called an indexed nested loop join. If the index is built as part of the query plan (and destroys the index immediately after the query completes), it is called a temporary index nested loop join. The query optimizer considers all of the

. "Clustered index Seek": Get records directly based on the clustered index, fastest!So, when a query is found to be slow, you can first check which operations are at a higher cost, and then see if those operations are "Table Scan" or "Clustered Index Scan" when looking for records, and if they are really related to these two types of operations, consider increasing the index to resolve them. However, when you increase the index, it also affects the m

What are SQL query statements in simple query and joint query? BR> 1. Simple Query A simple Transact-SQL query only includes the select list, from clause, and where clause. They indica

------------------------------------------------------------------------------------------------- TransAct --- SQL advanced query (lower)5: Use the having keyword to filter results6: Use the compute and compute by clauses7. Use nested Query8: Distributed Query E: Use the having keyword to filter the results.After quer

------------------------------------------------------------------------------------------------- TransAct --- SQL advanced query (lower)5: Use the having keyword to filter results6: Use the compute and compute by clauses7. Use nested Query8: Distributed Query E: Use the having keyword to filter the results. afte

| +------+--------+------+------+------+-----------+--------------+ 1 row in Set (0.00 sec) mysql> Example: Querying employee and Department tables using an inner join and displaying query results in ascending order of the age field mysql> mysql> Select Num,name,employee.d_id,age,sex,d_name,function-From employee,department where employee.d_id=department.d_id , order by age ASC; +------+----

example: Retrieves an example of information about a student who has at least one course pass: SELECT DISTINCT Student Table * From Students ' Table selection schedule WHERE Student table. Study Number = Select the timetable. The school number and the timetable. Grade =60 3. Sub-query A subquery is a series of SELECT statements. A SELECT statement can be

Combined Query of two SQL tables and database query under yii, Combined Query yiiJoin onFor example, two table queries: select u.username, t.title from user u join task t on u.id = t.id; Here, user u is used to simplify the join Operation of table names. If it is added to

getall method not only extracts all the data, in addition, we may also take out unnecessary field values. The getone method may not actually be of the int type for the table's primary key, so these definitions will be problematic... Therefore, we have seen many projects that use Orm. Whether all data is required or not, let's take it out first. Whether the primary key is of the int type or not, set a method there. It's a big deal to be an empty method, whether or not the current object requires

tables that are connected, and the number of rows returned to the result set equals the number of rows in the first table that match the query criteria multiplied by the number of rows in the second table that match the query criteria. For example, there are 6 categories of books in the titles table, and there are 8 publishers in the publishers table, the number

"peripheral application configurator" option, in the following aspect Property Window, change the status of AdHocremoteQueriesEnabled to true and click OK) Now you can execute the preceding query statement. This does not seem to satisfy our needs. For example, what should we do if we want to make such a query in our own program? I can't keep it on like this, but

SQL language query basics: Connection QueryYou 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

statement described above. Nesting means that when you parse the main SQL statement (the outside select) into the WHERE keyword, it goes into another SQL statement. In other words, the parser first finds the table student and loads the memory, and a pointer (for example, p1) points to the first record in the student table. Then into the where to parse the

SQL two simple paging query methods, SQL paging Query Method In the past, we may have used the skip and take method of linq for paging queries, but few of them write SQL paging queries by themselves, because most of the time, we are calling others' methods. I recently saw