Sandhya.np14 at 12:16, 6 February 2019

2019-02-06T12:16:42Z

Sandhya.np14 at 12:15, 6 February 2019

2019-02-06T12:15:36Z

Sandhya.np14 at 12:14, 6 February 2019

2019-02-06T12:14:17Z

PoojaMoolya: Created page with " {| border=1 | '''Time''' | '''Narration''' |- |00:01 | Welcome to the''' Spoken Tutorial''' on''' Updating Data''' |- |00:06 | In this tutorial we will learn about '''..."

2019-01-30T11:08:48Z

Created page with " {| border=1 | '''Time''' | '''Narration''' |- |00:01 | Welcome to the''' Spoken Tutorial''' on''' Updating Data''' |- |00:06 | In this tutorial we will learn about '''..."

New page

{| border=1
| '''Time'''
| '''Narration'''

|-
|00:01
| Welcome to the''' Spoken Tutorial''' on''' Updating Data'''

|-
|00:06
| In this tutorial we will learn about '''Update statement '''and '''Delete statement'''

|-
| 00:13
| To record this tutorial, I am using

'''Ubuntu Linux 14.04''' operating system

|-
| 00:20
| '''PostgreSQL 9.3.x'''

and '''pgAdmin 1.18'''

|-
| 00:28
| To follow this tutorial, you should have

Basic understanding of '''SELECT statement'''.

|-
| 00:35
| For more details, refer to the '''RDBMS PostgreSQL''' series on this website.

|-
| 00:41
| The '''update''' query is used to modify the existing records in a '''table'''.

|-
| 00:47
| We have to use the '''WHERE clause''' with the '''UPDATE statement''' to update the selected rows.

|-
| 00:53
| The syntax for '''update statement''' is shown here.

The '''columns''' to be modified are to be specified in the '''SET clause'''.

|-
| 01:03
| '''Column1''' would be assigned the '''value1''' and '''Column2''' would be assigned the '''value2''' and so on.

|-
| 01:12
| Other '''columns''' in the '''table''' will retain their previous values.

|-
| 01:17
| '''WHERE''' clause is used to find the exact row based on the specified '''condition''', to '''update''' it.

|-
| 01:24
| If no '''conditions''' are provided, then all '''records '''in the '''table''' will be updated.

|-
| 01:30
| Let's switch to '''pgAdmin''' main screen.

|-
| 01:34
| Now right-click on '''students''' node, then on '''View data''' and then on '''View''' '''All rows.'''

|-
| 01:43
| Notice here - it says the student whose id is ''''s008'''' is from ''''Chennai'''' city.

|-
| 01:51
| Now I want to change the city to ''''Bangalore'''' for this student.

|-
|01:56
| Now switch to the '''SQL editor''' window and type the '''update statement, '''as shown here.

|-
| 02:05
| This is a simple '''update statement '''which updates a single '''column'''.

|-
| 02:10
| The existing '''city '''value ''''Chennai'''' will be changed to ''''Bangalore'''' for the '''studentid s008''''.

|-
|02:18
| Execute the query.

We can see a message that the query is successful.

|-
| 02:24
| Let's retrieve the record to see the changes.

|-
| 02:28
| Clear the editor window and type this '''select statement.'''

|-
| 02:34
| Now, execute the query to see the output.

Note the updated value in the '''city''' field for student ‘'''s008’.'''

|-
| 02:45
|Next we will see how to update multiple '''columns'''.

|-
| 02:50
| Type the code. We can also update multiple '''columns '''by separating the '''column '''and value pairs, with commas, as shown here.

|-
| 03:02
| Remember, the '''date of birth column '''was '''null''' for the student ''''Ram charan''''.

|-
| 03:08
| This will update two '''columns, date of birth '''and '''city,''' with the values given in the '''update statement.'''

|-
| 03:16
| What will happen if you forget to give the '''where condition'''?

|-
| 03:20
| The entire '''students table '''will be updated with the given value.

|-
| 03:25
| Execute the query.

|-
| 03:28
|Let us see the updated value for the student name ‘'''Ram Charan’'''

|-
|03:33
|Type the '''select statement''' as shown here.

|-
|03:37
|Execute the query.

We can see the '''date of birth column''' and '''city column''' has been updated.

|-
| 03:46
| Next we will learn about the''' delete statement.'''

|-
|03:50
| The syntax for '''delete statement''' is as follows:

'''DELETE FROM table-name '''

'''[WHERE condition]'''

|-
| 03:59
| '''WHERE clause''' is used in the '''delete statement''' to delete specific rows which satisfy a particular '''condition'''.

|-
| 04:06
| All records will be deleted if no '''conditions '''are specified.''' '''

|-
| 04:11
| Let us see an example of the '''delete statement'''.

|-
| 04:15
|Switch to the '''SQL Editor''' window.

|-
|04:18
| Type the code as shown here.

This statement will delete the student record whose '''id '''is ''''s014''''.

|-
| 04:28
|Let us execute the query.

So one row is deleted now.

|-
| 04:34
| If you want to remove all the rows from the '''students table''', type '''delete from students'''.

|-
| 04:40
| There is no '''Where''' condition is specified here.

I'll not execute the query, as I don’t want to delete all the record.

|-
| 04:50
| Next let us see an example where we have two '''conditions''' in the '''DELETE statement'''.

|-
| 04:57
| Type the code as shown here.

|-
| 05:01
| This '''delete statement '''will delete the student details which satisfies two different '''conditions.'''

That is, the '''department''' should be ''''CS'''' and '''CGPA''' score should be less than 7.5

|-
| 05:15
| Let us execute this query.

|-
| 05:18
| In the output, we can see ‘'''0 rows affected'''’.

This indicates that no records are deleted.

|-
| 05:27
| That means there are no records in the '''student table''' which satisfies both the '''conditions'''.

|-
| 05:34
| With this we have covered the basics of common '''SQL statements''' such as

'''INSERT''' , '''SELECT''' , '''DELETE ''' and '''UPDATE ''' in this series.

|-
| 05:47
| These statements are otherwise called as '''Data Manipulation language.'''

'''DML''' is the short form of '''Data Manipulation Language.'''

|-
| 05:58
| It includes '''commands''' that are used to manipulate data in a '''database'''.

|-
| 06:04
| With this we come to the end of this tutorial.

Let us summarize.

|-
|06:10
| In this tutorial, we have learnt about the - '''Update statement '''and '''Delete statement'''

|-
| 06:17
| As an assignment, For '''studentid 's013'''', modify the student name from ''''Sharmila'''' to ''''Sharmila Babu'''' in the '''students table '''

|-
| 06:28
| Delete the students whose '''cgpa''' is less than 5

|-
|06:33
| The video at the following link summarises the Spoken Tutorial project.

Please download and watch it.

|-
|06:40
| The''' Spoken Tutorial Project''' Team

conducts workshops and gives certificates

For more details, please write to us.

|-
| 06:49
| Please post your timed queries in this forum.

|-
| 06:53
| Spoken Tutorial project is funded by NMEICT, MHRD, Government of India.

More information on this mission is available at this link.

|-
| 07:05
| This is Nirmala Venkat from IIT Bombay, signing off. Thanks for watching.

|}

@@ Line 88: / Line 88: @@
 |-
 | 02:10
-| The existing '''city '''value ''''Chennai'''' will be changed to ''''Bangalore'''' for the '''studentid'''
+| The existing '''city '''value 'Chennai' will be changed to 'Bangalore' for the '''studentid s008'''.
-'''s008'''.
 |-

@@ Line 88: / Line 88: @@
 |-
 | 02:10
-| The existing '''city '''value ''''Chennai'''' will be changed to ''''Bangalore'''' for the '''studentid
+| The existing '''city '''value ''''Chennai'''' will be changed to ''''Bangalore'''' for the '''studentid'''
-s008'''.
+'''s008'''.
 |-

RDBMS-PostgreSQL/C2/Updating-Data/English-timed - Revision history

Sandhya.np14 at 12:16, 6 February 2019

Sandhya.np14 at 12:15, 6 February 2019

Sandhya.np14 at 12:14, 6 February 2019

PoojaMoolya: Created page with " {| border=1 | '''Time''' | '''Narration''' |- |00:01 | Welcome to the''' Spoken Tutorial''' on''' Updating Data''' |- |00:06 | In this tutorial we will learn about '''..."