sql compare two tables and find records without matches

delete the child table records before deleting the primary table records.When you delete a data record, you tend to think of the delete and TRUNCATE statements immediately, but when you encounter a constraint between two or more tables, both statements may fail, and most of all, both commands can only manipulate one table at a time. So what do you do when you actually encounter all the

The SQL statement used to query multiple fields, query multiple tables, and delete duplicate records. SQL repeat record Query 1. Search for redundant duplicate records in the Table. duplicate records are determined based on a sing

There are many ways for SQLServer to search for and delete duplicate records in tables. Below I will list several commonly used SQL statements with good performance. If you need them, please refer to them. There are many ways for SQL Server to find and delete duplicate

to delete multiple tables in MySQL. 1. Delete all matching records with id values in Table T2. The Code is as follows: DELETE t1 FROM t1, t2 WHERE t1.id = t2.id or delete from t1 USING t1, t2 WHERE t1.id = t2.id 2. Find and delete no matching records in data table T2. The Cod

This article describes in detail how to sort combined queries in SQL statements. if you are interested, refer to the following. SQL statement (several tables are combined for query to obtain the first to tenth data records ): 1. for example, tables A, B, C, and D are ass

table is frequently updated operation, and whether the data to be read back will be modified, so the measurement whether to use with (NoLock) or based on the actual reality.Optimizing indexesAre there any missing or redundant indexes? Do you have any duplicate indexes?Handling deadlocksWe cannot observe the deadlock all the time, but we can record the deadlock of the system through the log, we can write the deadlock error of the system to the table, so it is convenient to analyze the cause of d

Use PLSQL to delete a large table with millions of records. This script uses the dbms_output.sleep () process to determine the maximum number of log files to be archived. You can use PL/SQL to delete a large table with millions of records. This script uses dbms_output.sleep () to delete a log file that needs to be archived. Use PL/

security', -,3), -('Mobike', $,3),('BMW', -,3),('Mercedes', -,3); - ---Check all bikes and show the owner name of the bike -SELECT B.*,m.manname from T_bike b joins T_man m on m.id=B.manid; in ---Query John Doe all bikes (internal connection: showing two tables with linked data) toSELECT b.*, m.manname from T_bike B joins T_man m on M.id=b.manid WHERE m.manname='John Doe'; +SELECT b.*, M.manname from T_man m joins T_bike B on M.id=b.manid WHERE m

Recently, the company's database found that table data has been removed, and some data tables have records of 0. So I want to find out which data tables in the database have records of 0 to narrow the analysis scope, the following SQL