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- What to do if sql fails to connect to the server
- SQL connection to the server failed because the database engine did not start. The solution: first click "Start->Programs->Microsoft SQL Server 2008->SQL Server 2008 Peripheral Application Configurator"; then click "Service" and select Start. Can.
- SQL 16979 2020-02-18 10:56:52
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- what is microsoft sql server
- Microsoft SQL Server is a comprehensive database platform that provides enterprise-level data management using integrated business intelligence tools; the Microsoft SQL Server database engine provides more secure and reliable storage functions for relational data and structured data.
- SQL 7602 2020-02-18 10:20:31
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- Usage of inner join in sql
- INNER JOIN is a multi-table connection keyword in SQL. The syntax is: SELECT * FROM table1 INNER JOIN table2 ON table1.field1 compopr table2.field2, which is used to query related data between two tables.
- SQL 11726 2020-02-14 16:22:45
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- What does where 1=1 mean in SQL statement?
- Where 1=1 in the SQL statement is automatically generated by the program to avoid grammatical errors caused by the first word after the where keyword being "and".
- SQL 7639 2020-02-13 17:19:58
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- The principle of SQL injection attack
- The principle of SQL injection attack: A malicious user inserts a SQL statement into the request content during the process of submitting a query request. At the same time, the program itself overly trusts the user input content and fails to filter the SQL statement inserted by the malicious user, causing the SQL statement to be directly Server-side execution.
- SQL 16255 2020-02-13 17:13:33
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- What is the SQL statement to create a view?
- SQL creates a view using the create view statement. The specific usage is as follows: create view viewname as select * from <name of table> where <some restrictions>.
- SQL 33154 2020-02-13 16:56:09
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- Usage of case when in sql
- Case has two formats: simple case function and case search function. The simple case function is relatively simple to write, but compared with the case search function, there are some functional limitations, such as writing predicates.
- SQL 22267 2020-02-13 16:35:04
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- What does 'select 1 from table' mean?
- "Select 1 from table" means to check whether there are records in the table. 1 is a constant, and the value of all rows found is it. In terms of efficiency, 1>column>*, because 1 does not need to look up the dictionary table .
- SQL 20413 2020-02-13 16:13:14
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- How to delete data using sql statement
- SQL can use the delete statement to delete data. The syntax is "delete from table name where...". When where does not match any records, no data will be deleted. When the where statement is not written, the table will be deleted. All data.
- SQL 41984 2020-02-07 13:16:18
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- sql intercepts the first digits of a string
- In SQL, you can use the LEFT function to get the first few digits of a string. The syntax is "LEFT(string,length)", string is the intercepted string, and length is the length to be intercepted, for example, LEFT("www.php. cn",3) can intercept www.
- SQL 23741 2020-02-07 12:37:29
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- Functions of sql language
- The functions of SQL language: 1. Data definition function, which can define the three-level schema structure of the database, namely external schema, global schema and internal schema structure; 2. Data manipulation function, including data insertion, deletion and deletion of basic tables and views. Modification; 3. The data control function is mainly to control the user's access rights to ensure the security of the system.
- SQL 26471 2020-02-06 13:16:16
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- sql statement to modify data
- SQL uses the update statement to modify data. The syntax format is "update <table name> set field 1 = value where <condition>". When multiple values need to be modified, each value in the set clause can be separated by commas.
- SQL 33053 2020-02-06 11:02:24
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- SQL fuzzy query statement
- The syntax of the sql fuzzy query statement is "SELECT field FROM table WHERE certain field Like condition", among which conditions, SQL provides four matching modes, namely: [%], [_], [[]], [^].
- SQL 31537 2020-02-06 10:50:52
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- What is the execution order of sql statements?
- Execution order: the from clause assembles data from different data sources; the where clause filters record rows based on specified conditions; the group by clause divides the data into multiple groups; uses aggregate functions for calculations; uses the having clause to filter Group by; evaluate all expressions; select set output, etc.
- SQL 14713 2020-01-07 15:15:50
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- What is the usage of in in sql
- The IN operator allows us to specify multiple values in the WHERE clause. Syntax: SELECT column_name(s), FROM table_name, WHERE column_name IN (value1, value2,...).
- SQL 53798 2020-01-07 15:02:51
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