ies payroll

figured out what schema is, so let's talk about why schema is needed. Continue.2. Why do I need the mode? In many cases, I need to know what the concept is and why it is needed. In this way, we will remember more firmly, become more interested, and make changes and innovations. Why do we need a mode? We know that users need a password to log on, and the mode corresponds to users one by one. By the way, this is a security consideration. Think about it. James has a table called salary, and Xiaoho

the file. This text can be localized, and it should be the same as all files associated with the same WEB service extension. /s Computer Runs the script on the specified remote computer. Type the name or IP address of the computer without the backslash. By default, the script runs on the local computer. /u [domain\]user Runs the script with the permissions of the specified user account. The account must be a member of the Administrators group on the remote computer. By default, the script r

"Command:Select Supplier name from supplier where supplier name like '% plant% ';Results:11. Find out which suppliers are not in XianCommand:SELECT * FROM supplier where address! = ' Xian ';Results:12. Find the warehouse that is not in BeijingCommand:SELECT * FROM warehouse where city! = ' Beijing ';Results:13. Sort out all employees ' information in descending order of wagesCommand:SELECT * FROM Employee ORDER by salary Desc;Results:14. Sort by warehouse number in ascending order and then desce

√ √ √ Read committed X √ √ REPEATABLE READ X X √ Serializable X X X Note: We discuss the isolation level scenario, mainly in the case of multiple transactions concurrency, so the next explanation is around the transaction concurrency. READ UNCOMMITTED not submitted The company paid, the leader of the 5000 yuan to the Singo account, but the transaction did not submit, and Singo just to check the accoun

wages issued to Singo is not correct, is 2000 yuan, and then quickly rolled back to business, modify the amount, the transaction will be submitted, and finally singo the actual salary of only 2000 yuan, Singo empty joy a game. The above situation, that is what we call dirty Read, two concurrent transactions, "transaction A: lead to Singo payroll", "Transaction B:singo query Payroll account", transaction

yuan, and then quickly rolled back to business, modify the amount, the transaction will be submitted, and finally singo the actual salary of only 2000 yuan, Singo empty joy a game.The above situation, that is what we call dirty read , two concurrent transactions, "transaction A: lead to Singo payroll", "Transaction B:singo query Payroll account", transaction B read the transaction A has not yet committed d

that the amount of wages issued to Singo is not correct, is 2000 yuan, and then quickly rolled back to business, modify the amount, the transaction will be submitted, and finally singo the actual salary of only 2000 yuan, Singo empty joy a game.The above situation, that is what we call dirty Read, two concurrent transactions, "transaction A: lead to Singo payroll", "Transaction B:singo query Payroll accoun

+count87)) Dbms_output.put_line ('count81:'||count81) Dbms_output.put_line ('count82:'||count82) Dbms_output.put_line ('count87:'||count87)End; / Example 2: Raise wages for employees From the minimum wage up to 10% per person, but the total wage can not exceed 50,000 yuan, please calculate the number of wages and wages after the wage increase, and output wage increase and payroll. Analysis: SQL statement:select Empno,sal from emp order by Sal; ---> Cu

, is 2000 yuan, and then quickly rolled back to business, modify the amount, the transaction will be submitted, and finally singo the actual salary of only 2000 yuan, Singo empty joy a game.The above situation, that is what we call dirty Read, two concurrent transactions, "transaction A: lead to Singo payroll", "Transaction B:singo query Payroll account", transaction B read the transaction A has not yet com

, very happy. Unfortunately, the leadership found that the amount of wages issued to Singo is not correct, is 2000 yuan, and then quickly rolled back to business, modify the amount, the transaction will be submitted, and finally singo the actual salary of only 2000 yuan, Singo empty joy a game.The above situation, that is what we call dirty Read, two concurrent transactions, "transaction A: lead to Singo payroll", "Transaction B:singo query

Singo is not correct, is 2000 yuan, and then quickly rolled back to business, modify the amount, the transaction will be submitted, and finally singo the actual salary of only 2000 yuan, Singo empty joy a game.The above situation, that is what we call dirty Read, two concurrent transactions, "transaction A: lead to Singo payroll", "Transaction B:singo query Payroll account", transaction B read the transact

in queries1. SELECT * from Tb_grade WHERE (Foreign Languages > "High >") and Chinese >802. SELECT * from Tb_grade WHERE foreign languages > and High > 90Ten sorting, grouping statistics1. SELECT Publisher sum (amount) as total amount from Tb_book GROUP by publishing house2. SELECT title, publisher, sum (amount) as total amount from tb_book WHERE publishing house = ' People mail ' GROUP by all, title, publishing house3. SELECT Department, Gender, AVG (payrol