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- What are the core statements of SQL language?
- The core statement of the SQL language is the query statement. There are many important statements in SQL, such as [CREATE DATABASE] to create a new database and [ALTER DATABASE] to modify the database.
- SQL 5489 2020-11-25 11:12:06
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- What are the aggregate functions in SQL Server?
- Aggregation functions include: 1. AVG, returns the average value; 2. COUNT, returns the number of items in the specified group; 3. MAX, returns the maximum value of the specified data; 4. MIN, returns the minimum value of the specified data; 5. SUM, Returns the sum of the specified data; 6. VAR, returns the statistical variance of all values in the given expression; 7. VARP, etc.
- SQL 28880 2022-03-24 15:40:31
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- What is the difference between Hive-sql and sql?
- Differences: 1. Hive-sql does not support equivalent connections, but sql does; 2. Hive-sql does not support "Insert into table Values()", UPDATA, and DELETE operations, but sql does; 3. Hive-sql does not support transactions , and sql supports.
- SQL 20680 2020-11-13 11:20:23
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- How to write sql modification statement
- How to write the sql modification statement: [UPDATE table name SET column name = new value WHERE column name = certain value]. The update statement is used to modify data in the data table.
- SQL 67852 2020-11-13 09:52:54
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- How to create a table in sql
- In sql, you can create a data table through the syntax "CREATE TABLE table name (column name 1 data type, column name 2 data type,...)".
- SQL 50421 2020-11-04 13:43:24
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- What are the sql commands to delete tables?
- SQL commands to delete tables: 1. drop, deletes content and definitions, and releases space; 2. truncate, deletes content, releases space but does not delete definitions; 3. delete statement is used to delete rows in the table; 4. truncate table deletes the table All rows in , but the table structure and its columns, constraints, indexes, etc. remain unchanged.
- SQL 34908 2020-10-30 14:15:48
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- How to start sql server service
- How to start the sql server service: 1. Click the start menu and find the sql server folder; 2. Open [Configuration Tools] and [sql server configuration manager] in sequence; 3. Right-click the sql server service and click [Start] .
- SQL 13891 2020-10-30 16:57:26
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- What are the common SQL query statements?
- Common SQL query statements include: 1. View table structure [SQL>DESC emp;]; 2. Query all columns [SQL>SELECT * FROM emp]; 3. Query specified columns [SQL>SELECT empmo,]; 4. Query Specify the row [SQL>SELECT * FROM].
- SQL 10107 2020-10-26 15:31:41
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- How to remove duplicate queries in sql
- SQL deduplication query method: Duplicate records are judged based on a single field peopleId, and deleted using the statement, the code is [where peopleId in (select peopleId from people group by peopleId].
- SQL 15942 2020-10-10 11:37:29
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- What is the function of where phrase in sql command?
- The function of the where phrase in the sql command is to specify the selection criteria and filter records; if you need to conditionally select data from the table, you can add the WHERE clause to the SELECT statement.
- SQL 10409 2020-08-31 17:10:21
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- What is a description of how a database is physically stored called?
- The description of how a database is physically stored is called the "internal schema". The internal schema gives the physical storage structure and physical access methods of the database, such as the file structure, index, clustering, hash and other access methods and access paths of data storage. The physical properties of the internal schema are mainly reflected in the operating system and file level. superior.
- SQL 11791 2020-08-31 16:29:51
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- What is the operation called to find tuples that satisfy a given condition from a relation in a relational database?
- In a relational database, finding tuples that satisfy a given condition from a relationship is called selection. The condition is given as a logical expression, and the tuple with a true value will be selected.
- SQL 18924 2020-08-31 16:11:26
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- What software is used to implement various data operations in the database?
- The software used to implement various data operations in the database is: database management system; the database management system can directly operate the data in the database. Database management system is a large-scale software that manipulates and manages databases and is used to establish, use and maintain databases; it provides unified management and control of databases to ensure the security and integrity of the databases.
- SQL 16106 2020-08-29 15:25:06
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- What three common functions does the sql language have?
- The three common functions of SQL language are: 1. Data definition; it can define the three-level schema structure of the database, namely external schema, global schema and internal schema structure. 2. Data manipulation; including data insertion, deletion, modification and query functions for basic tables and views. 3. Data control; mainly controlling user access rights to ensure system security.
- SQL 37324 2020-08-29 13:46:01
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- SQL server high concurrency generates unique order number
- We can use stored procedures and data tables to build a table and create stored procedures. The stored procedure is responsible for generating order numbers, and the table is responsible for handling uniqueness issues.
- SQL 2730 2020-08-29 12:01:38
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