csx payroll

√ √ √ 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