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- What are non-relational databases?
- Non-relational databases include: 1. MongoDB, which is a document-oriented open source NoSQL database; 2. Cassandra, which was developed by Facebook for inbox search; 3. Redis, which is the most famous key-value store.
- SQL 37022 2020-07-01 15:24:49
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- What are distributed databases?
- Distributed databases include: 1. In the direction of the Internet of Things, time series database products meet the collection, storage and statistics of IoT data, such as InfluxDB, Kudu, kdb, and OpenTSDB; 2. In the direction of transaction relationships, Ant Financial Oceanbase and Tencent TDSQL.
- SQL 20367 2020-07-01 15:14:16
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- What is the priority of SQL statement execution order?
- The execution order priority of SQL statements from high to low is: the statement after the from keyword, the statement after the where keyword, the statement after "group by", the statement after select, and the statement after "order by".
- SQL 22680 2020-07-01 09:44:34
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- What is SQL Interface
- SQL Interface refers to the SQL interface, which means that it accepts the user's SQL commands and returns the results that the user needs to query. For example, select from is to call the SQL Interface.
- SQL 4004 2020-07-01 09:10:36
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- How to create student table using sql statement?
- Steps: 1. Open "sql server"; 2. Use "creat table student();" to create a table; 3. Use "char()" to define the type of name, gender, and age; 4. Use "insert into student values" ();" Just define the table attributes.
- SQL 35282 2020-06-30 10:16:34
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- What is slow query
- In addition to using EXPLAIN to output the execution plan, the method of analyzing MySQL statement query performance can also allow MySQL to record statements that query more than the specified time. We call SQL statement queries that exceed the specified time "slow queries".
- SQL 5312 2020-06-29 16:22:37
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- What does database read-write separation mean?
- The separation of database read and write means to ensure the stability of database products. Many databases have dual-machine hot backup functions. That is to say, the first database server is a production server that provides external addition, deletion, and modification services; the second database server mainly performs read operations.
- SQL 8240 2020-06-29 13:24:15
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- How to pronounce sql server?
- The pronunciation of "sql server" is [sikəu 'sə:və]. "SQL Server" is a relational database management system launched by Microsoft; it has the advantages of ease of use, good scalability, and a high degree of integration with related software.
- SQL 20204 2020-06-24 09:55:56
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- What are the four parts of the function of sql?
- The four parts are: 1. Data definition, which is used to define the creation and undoing operations of SQL schema, basic tables, views and indexes; 2. Data manipulation, which is divided into two categories: data query and data update; 3. Data control, including basic Authorization of tables and views, description of integrity rules, transaction control, etc.; 4. Regulations on the use of embedded SQL.
- SQL 20418 2020-06-23 17:13:00
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- What needs to be modified to ensure data independence of the database?
- To ensure the data independence of the database, what needs to be modified is the mapping between the schema and the internal schema. DBMS provides two layers of images, namely: external schema/schema image and schema/internal schema image; the image from the external schema to the schema ensures the logical independence of the data; the image from the schema to the internal schema ensures the physical integrity of the data. independence.
- SQL 13044 2020-07-23 13:13:58
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- How to create a database in SQL Server?
- SQL Server database creation method: first start the "SQL Server Management Studio" software; then log in to the software with a Windows account by default; then right-click the database and select [New Database]; finally enter the database name and save the database.
- SQL 4912 2020-06-23 13:47:16
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- How to use update statement to associate multiple tables?
- Methods for multi-table association in update statements: 1. Use the link of where clause, the code is [where exists (select1fromtmp_cust_city b]; 2. The modified value is calculated from another table, the code is [from tmp_cust_city b].
- SQL 13245 2020-06-29 17:13:10
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- What is SQL query and what are its characteristics?
- SQL query is to establish contact and communicate with various databases. Its characteristics are: 1. Real client/server architecture; 2. Graphical user interface, making system management and database management more intuitive and simple; 3. Rich Programming interface tools provide users with greater options for programming.
- SQL 10735 2020-06-22 16:56:06
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- What is the method to add data in batches using sql statements?
- Methods for adding data in batches using SQL statements include: 1. Use the statement [insert into table name (field) values (field value)] to execute them one by one; 2. Use the statement [insert into table name (field) values (field value 1), (field value 2), (field value)] to execute in batches.
- SQL 11277 2020-06-22 16:45:14
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- What are the SQL statements to delete table fields?
- The SQL statements to delete table fields are: 1. Delete columns without default values. The code is [alter table Test drop COLUMN BazaarType ]; 2. Delete columns with default values, the code is [alter table Test DROP COLUMN].
- SQL 6164 2020-06-22 15:35:19
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