Because sql statements are not case sensitive, all commands in this article use lowercase for convenience
day 01 first knowledge of Mysql and DDL data definition languageday 02 DML data operation languageday 03 DQL data query language -- a first glimpseday 04 DQL data query language - single table query - a slight succ ...
Posted by kampbell411 on Tue, 29 Mar 2022 07:33:25 +0300
For database Experiments 1 and 2 and database creation, please Refer here What is a cursor? Cursor is a data buffer set up by the system for users to store the execution results of SQL statements. Each cursor area has a name. Users can use SQL statements to obtain records from the cursor one by one, assign them to the main variable, and submit ...
1. Key words of trigger: trigger 2. Overview: it is a special stored procedure, and the stored procedure is a special function When the DML (data manipulation language) statement is executed, the trigger will be triggered and executed automatically, rather than requiring manual call like a function. 3. Syntax of trigger:
Posted by headmine on Sun, 27 Mar 2022 09:15:10 +0300
Experimental reportexperimentRead data table 1-table 4 and consider whether it is reasonable to add constraints to each fieldWrite T-SQL statements, create tables and constraintsView information about creating tablesVerify data integrity by inserting data into the table and answer the appropriate questionsExperimental task 1Using T-SQL to compl ...
Posted by Exemption on Sat, 26 Mar 2022 22:05:12 +0300
Get historical execution plan: AWR/StatsPack SQL Report
When a SQL performance problem occurs, you may want to look at the historical execution status to confirm whether there is any change. In this case, Oralcle's AWR/StatsPack SQL report is very useful.
AWR SQL Report
The information obtained by the AWR (Automatic Workload Repository) ...
Posted by samafua on Sat, 26 Mar 2022 17:25:56 +0300
Modify database table
Modify table name:
alter table Old table name rename as New table name
Add table fields
alter table Table name add Field column properties
For example: alter table student age int(11)
Modify the fields of the table
alter table Table name modify Field column properties;
For example: ...
Posted by jyushinx on Sat, 26 Mar 2022 12:26:12 +0300
There are 33 national standard attribute table excel files, and the database table needs to be built according to these standard attribute tables. The format of each excel is as follows:
For such heavy and basically brainless work, I choose Python to do it:
Posted by LiamOReilly on Sat, 26 Mar 2022 06:52:41 +0300