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1. cursor Using cursors to solve the problem that sql statements can't handle row records, we want to be a traversal array in java. BEGIN DECLARE river_id VARCHAR(32); -- Custom variable DECLARE river_name VARCHAR(50); -- Custom variable DECLARE done INT DEFAULT FALSE; -- Traverse d ...

I. what is trigger trigger is a method provided by SQL server to programmers and data analysts to ensure data integrity. It is a special stored procedure related to table events. Its execution is not called by programs or started manually, but triggered by events. (--- from Baidu Encyclopedia) Simp ...

Preface The main function of index is to restrict and speed up the search. The ORM framework (sqlalchemy) uses classes and objects to operate the database.   Types of indexes By category 1. General index: can speed up search 2. Primary key index: can speed up search, cannot be empty, cannot be duplicate 3. Unique index: accelerated searc ...

Because I have never used the database to push data to the java interface before, in order to achieve this demo, I step by step step stepping on the pit!!! The function and application scenario of this article: using database to push data actively, realizing real-time updating of front-end page dat ...

Links to the original text: https://www.cnblogs.com/kdp0213/p/8532838.html Differences between the cmd.Parameters.Add method and the VS Parameters.AddWithValue("@parameter", value) method In the past, when using command method to a ...

Use django to connect to SQL Server, and pyodbc to connect to multiple databases. pyodbc, the SQL that runs the query, is very simple: import pyodbc connection = pyodbc.connect('DRIVER={SQL Server Native Client 10.0};SERVER=127.0.0.1;DATABASE=DB_name;UID=User_Name;PWD=PassWord') curs = connection.execute('select * from table') #curs.fetchone( ...

Author: Yang Taotao background Today's article comes from a question asked by today's customers. Problem: I'm migrating from Oracle to MySQL, and the data has been converted to a simple INSERT statement. Because there are many statements, I don't know how to locate the wrong statement every time I import it. If there are fewer INSERT statement ...

Summary A few days ago, a client consulted about MySQL recursive query method. At that time, he had a simple understanding and felt that recursive query logic level is a special query method. However, it was later found that this is a very common query requirement, such as folding display of some comment floors, various flow charts and other re ...

This time I'll go on to talk about MySQL stored procedures: Let's first look at its multi-branch control structure case: The statement of case is simple: case variable name when condition 1 then output result 1; when condition 2 then outputs result 2; ...... end case;   So let's build a stored procedure to implement it: create proce ...

There is such a requirement, a form main table, an extended list, query to expand the list of multi-row into the main table multi-column. such as dt_zhubiao [main table] id type title 1 1 Form 1-1 2 1 Forms 1-2 3 2 Form 2-1 4 2 Form 2-2 dt_kuozhanbiao [Extended Table] id formid name title value 1 1 ext_ ...