When performing database operations, sometimes we need to synchronize a field in the two associated tables, that is, assign the value of field A in table 1 to field B in table 2, and table 1 and table 2 are associated through field C. The SQL statement is as follows (Sql server and MySql are written slightly differently):
SQL Sever：
写法1： update t2 set t2.B=t1.Afrom Table2 t2 ,Table t1 where t2.C2=t1.C1
写法2： UPDATE Table2 SET B= (SELECT A FROM Table1 WHERE C1=Table2.C2)
MySQL:
update Table2 inner join Table1 on Table2.C2=Table1.C1 set Table2.B=Table1.A
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