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Xiaobian to share with you what is responsible for the database query operation database language, I believe most people do not know how, so share this article for your reference, I hope you read this article after a great harvest, let us go to understand it together!

The database languages responsible for query operations in the database are: Data Manipulation Language (DML), which is mainly responsible for basic operations of data, including query, addition, deletion, modification and other operations.

Database languages include the following three points:

Data Definition Language (DDL) and its translation program: mainly responsible for data schema definition and data physical access construction.

Data Manipulation Language (DML) and its compiler (or interpreter) program: mainly responsible for the basic operations of data, including queries and add, delete, modify and other operations.

Data control language: responsible for interpreting the meaning of each control command and deciding how to execute the control command.

Among them, the database language responsible for query operation in database is Data Manipulation Language (DML), through which users can realize basic operation on database.

operation

insertion operation

Insert data into a database at a specified location, such as Append, which adds records at the end of a database file, and INSERT, which adds records before specified records.

delete operation

Delete A group of records in a database that no longer needs to be retained, such as Delete to mark a record in a database for deletion. PACK is to completely erase the record marked with deletion mark. ZAP removes all records from the database file.

change operation

Modify records or database schema, or generate new relational schema and records on the basis of existing data, such as Join operation and projection operation.

sort operation

Change the arrangement of physical storage. For example, the SORT command sorts the records in the DBF file by the specified keyword string. From a physical storage point of view, the database has changed, but from a logical point of view (or set theory point of view), the new relationships are equivalent to those before sorting.

retrieval operation

Retrieves data from a database that meets the criteria, which can be a data item, a record, or a group of records. For example, BROWSE unit realizes browsing operation of data. SELECT selects records that satisfy certain conditions and ranges.

The above is what is responsible for database query operation database language all the content, thank you for reading! I believe that everyone has a certain understanding, hope to share the content to help everyone, if you still want to learn more knowledge, welcome to pay attention to the industry information channel!

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