All language subtitles for 13. DELETE

In the last video we learnt how to update rows in a table
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now let us see how to delete one or more rows from a Table
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To delete rows, delete query is used. The syntax of delete query is
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Delete from
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Mention the table name
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and then give the condition
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for the rows to be deleted
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Condition will be given again using the
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Where clause
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Let us see some example
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If you want to delete a single row
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We can just run a query
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to delete from customer table
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Where customer ID is
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six
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If you want to delete multiple rows
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Say
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If you want to delete all the customers who are less than 25 years old
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We will write delete from customers
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From customer table where
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Age is less than 25
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If you want to delete all the rows of the table
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we will use
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Delete
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From customer table and not mention any condition
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Let's go to PG admin and write these 3 queries
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Now let us delete the customer with Customer Id 6
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We'll write delete from
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Customer table
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Where
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Cust ID
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Is equal to 6
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Let us run this
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And let us see the result
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If you remember earlier we had 10 records after deleting this one record
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We'll be having
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9 records
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We have 8 records in the result because 2 customers had customer ID
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Six
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Now
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If you want to delete, all the customers
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Whose age is more than 30 years
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So if we look at the data
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Customer with customer ID 1
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And customer ID
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8
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Customer ID 4
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These three customers have
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age more than 30 years. Let us delete these three customers from our database
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Delete from customer table
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Where age
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is equal to
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age greater than 30. Let's run this.
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It ran successfully
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Let us run the
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Select query
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You can see only
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5 remain
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earlier we had 8. 3 customers had age more than 30. Now no customer has age more than 30
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You can delete all the rows of this table
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To do that
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we will not specify any condition we will just
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Tell it to delete
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From customer table and that's it
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If we run this query everything from the table will be deleted
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Let us run this select command
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You can see only column names are there
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That's all
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what this table now has, it has no rows
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No data in it
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So that's how you delete data from a Table
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In the next lecture
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We will learn, how to change
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The
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Structure of the table
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Structure of the table is comprised of the columns column names or the constraints
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added to the columns, all these constitute the structure of the table and we will learn how to change the structure of the table