Monday, October 12, 2009

Creating Joins with the USING Clause

  • If several columns have the same names but the data types do not match, the NATURALJOIN clause can be modified with the USING clause to specify the columns that should be used for an equijoin
  • Use the USING clause to match only one column when more than one column matches
  • Do not use a table name or alias in the referenced columns
  • The NATURAL JOIN and USING clauses are mutually exclusive
Joining Column Names :



Retrieving Records with the USING Clause :
  • SELECT emp.empno, emp.ename, dept.loc, deptno FROM emp JOIN dept USIN (deptno) ;

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