Summarize the SQL Experience Learned within one week (1) and the SQL experience within one week

Summarize the SQL Experience Learned within one week (1) and the SQL experience within one week

-Weekly learning Summary

1. The data type defined in Table creation is inconsistent with the data type when data is inserted.

2. Pay attention to the difference between join and left join.

3. group by Principle: columns without Aggregate functions in all columns after select must appear behind group.

4. When calculating the ranking, remember to use with ties if the same ranking appears.

5. order by is sorted in ascending order by default. It can also be identified by ASC and desc in descending order.

6. distinct deduplication

7. Batch insert into table_name

Select __________ union

Select __________ union

Select ___________

The difference between union all and union.

8. The difference between truncate table name and drop table name is that drop only deletes the table content. truncate is like deleting the memory space of the table.

This is also the method for restoring auto-increment segments to 1.

9. Foreign key constraints are not allowed when you delete a table.

10. Use the case statement to replace the rows and columns of the score.

11. When two tables have mutual foreign key constraints, we should put these two foreign key constraints together during table creation.

When inserting data, the foreign key constraint of one table is set to null first, then the data of the other table is inserted, and the foreign key constraint

Update data.

12. Transactions and stored procedures-Example of bank transfers.

13. The view only gives the user the permission to access a table. The hidden method only displays the terminal to the user.

14. A table can have only one clustered index. There is only one physical sorting method for data, and multiple non-clustered sorting can be performed.

15. trigger my simple understanding is that when you operate on one of the tables, it will affect other tables. At this time, a trigger is required to trigger the modification of other table content.

SQL practice example

After three weeks of software testing training in ruankosoft excellence lab, I learned a lot from the methods and skills of software testing that I have no experience in software testing. Write a bit of practical experience and share it with you.

During my college career, I majored in communication engineering. I was originally planning to work on the network, and I was interested in the knowledge of activity directories, databases, operating systems, and so on. After this theoretical study, I learned that to do a good job of software testing, the required knowledge is not only about testing. The knowledge of networks, databases, operating systems, and so on is very helpful. This makes it clear that I will learn more in the future. While learning software testing continuously, I should continue to learn other related knowledge in depth.

Through this study, we have a deep understanding of the entire software testing industry. In the past, we thought that software testing was just a boring and repeated use of tested software to identify exceptions. We thought that software testing was not important, and it was inferior to development. Now I have realized the importance of software testing. software testing is an indispensable part of the software industry's development towards the era of software industrialization and production. It is an indispensable part to ensure that the software quality meets the needs of customers. Software testing is a new career in China and has developed late, but its importance is being paid attention to by the industry.

This course laid a good professional foundation for our future software testing work and laid a solid theoretical foundation for our further study and improvement. We have a preliminary understanding of the test process. The test plan, test design, test development, test execution, test evaluation, and test report run through the entire software development process. Each phase of unit testing, integration testing, system testing, and verification testing should be based on user requirements. Although these basic concepts are abstract, they will be of great benefit to future practices.

Let's change it for your reference!

How to Learn about database

Question added: Learning Experience of about one thousand two hundred words. The instructor asked me to help you learn SQL statements, INSERT UPDATE DELETE SELECT, and learn how to connect to and create statements.