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SQL JOIN

SQL JOIN - SQL教程

课程: SQL Weekly Tips

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SQL JOIN

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- [Instructor] SQL uses joins to connect two relational databases together. In order to effectively use SQL, you must understand how joins work. And there are several of them. It's going to take some time to work your way through 'em. Incidentally, if you're confused about joins, join the rest of the SQL community. Joins are complex, but once you understand them, your work with SQL will benefit. So let's dive right in and look at the simplest of all joins. I've set this up in line three through 10. And if I select those lines, and then use Visual Studio's command E, command E, I can execute that SQL. On the right hand side, you'll see that we've got some results. The first column is titled first name, the second is last name, and the third is postal code. And you can see that those are generated from our code in line three, four, and five. Lines six and seven of the SQL code identify fields called…

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