How to use Sql Self Join. A self join compares values within a single table.
Since we are using the same table more than once, we need to distinguish them by using different aliases. To qualify a column name, we use the alias name. See the following two different ways to write sql self join.
Use PUBS datatabase. Sometimes a book has more than one authors. By using just TitleAuthors table, find a list of books that have more than one authors. For this sql self join exercise, just show TitleID and AuthorsID.
Please note that the solution using sql self join is not the only way to answer that question. You can utilize Sql Count or Sql Subquery to solve this. Please try this yourself in your Sql Server Express environment.
You can find the solution in the Problems and Solutions page.
Sql Create Database
Use this to create a database.
Sql Create Table
This Sql Create Table will be used very often throughout the tutorial. It is used to create a table, in our case, mainly to create sample tables.
Sql Alter Table
Used less often, but it is very handy to know this command. With this you can basically edit a table structure.
Sql Drop Table
Used to delete a table, not just the content. This command is also used very often during the tutorial. So, you need to master this too.
To add rows to a table, you use Sql Insert command. There are two methods, one is with the VALUES keyword and second is with a SELECT statement.
To change existing rows, you use Sql Update command. You can use it to change values in a single row, groups of rows or all rows. You can also update a table based on values in other tables.
To remove rows, you use Sql Delete command. You can delete one rows, group of rows or all rows. You can also delete rows based on values in other tables.
The core of Sql, selecting data from table.
Eliminating duplicate values in the output.
Conditionally selecting rows from table.
Pattern searching for conditions in Where or Having clause
Added to conditions to show results between two values.
It enables us to specify multiple values, either as a list or a subquery.
Sql And Or
Connecting two or more conditions in the Where or Having clause.
Counting number of rows.
Getting the sum of a field
This function will return the highest value.
This function will return the lowest value.
This function will return the average value.
Sql Order By
Sorting the output
Sql Group By
Grouping rows into sets.
To filter the result of aggregation
Advanced Sql Tutorial
Sql Inner Join
Use Sql Join to retrieve data from more than one table in just one Select statement.
Sql Outer Join
An Sql outer join shows the join, and all the rows that do not qualify.
A nested Sql Select inside the WHERE clause of another Sql Select statement.
Merging two or more queries into one result. Rows are appended from one queries to the other.
Return from Sql Self Join to Advanced Sql Tutorial
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