One attribute in a table became corrupted after a certain point in a table of mine. I want to delete every pat_coun attribute if it has an ID that begins with 11 (number, not text). So I don't want to get rid of any of the records in the database, just clear out the attribute pat_coun if it's ID begins with 11
DELETE pat_coun from myTable
WHERE id %11
Just want to make sure this is right before I go deleting stuff. Thanks.
To clear out an attribute, do NOT use the DELETE function! That deletes a row from your table!
You need to use UPDATE instead:
UPDATE myTable
SET pat_coun = NULL
WHERE id LIKE '11%'
If you want to delete a record (a row) you can use
DELETE FROM myTable
WHERE condition
If you just want to "clear" a particular column you should use
UPDATE myTable
SET pat_coun = 0 // or NULL or whatever you please
WHERE condition
For condition IMHO you should convert your number to string and check like this
WHERE CONVERT(VARCHAR(20), pat_coun) LIKE '11%'
try this
update myTable
set pat_coun = null
where id like '11%'
Related
I have a situation where I want to show a value that corresponds to one field in a table but in all rows. What is better is to show you an example in a screenshot:
What I want is to have the value of 3807 in every row? How can I do that?
THank you in advance.
Try using MAX as an analytic function:
SELECT
site_id,
bt_max_speed,
MAX(bt_max_speed_on_site_coverage) OVER (PARTITION BY site_id) bt_max_speed_on_site_coverage
FROM yourTable
ORDER BY site_id;
If you simply want to update one column so it has same value for all rows you can just use UPDATE without any conditions
UPDATE <table_name> SET <column_name> = <value>
In your case it would look like this, but with replaced with actual name of your table
UPDATE <table_name> SET bt_max_speed_on_site_coverage = 3807
What is the best way to modify the latest added row without using a temporary table.
E.g. the table structure is
id | text | date
My current approach would be an insert with the postgresql specific command "returning id" so that I can update the table afterwards with
update myTable set date='2013-11-11' where id = lastRow
However I have the feeling that postgresql is not simply using the last row but is iterating through millions of entries until "id = lastRow" is found. How can i directly access the last added row?
update myTable date='2013-11-11' where id IN(
SELECT max(id) FROM myTable
)
Just to add to mvb13's answer (since I don't have enough points to comment directly yet) there is one word missing. Hopefully, this will save someone some time from working out the correct syntax LOL.
update myTable set date='2013-11-11' where id IN(
SELECT max(id) FROM myTable
);
How can I delete the value of a field from a database, using query code? I only know where the field is located in the database. (ex: column['phone number']row[3])
It should be something like this "DELETE FROM ... WHERE ..."
There is nothing like delete the field in database i.e. if you want to remove the complete row then you can do that easily like this
DELETE FROM TABLE WHERE COLUMN1=#myValue
But if you wanted to remove one value of the row in that case you should update that value as NULL
UPDATE TABLE SET COLUMN1=NULL WHERE COLUMN1=#myValue
I have used where clause from my imagination. you can always use whatever you want.
The DELETE statement allows you to delete RECORDS.
When you want to set a field to an empty value, use the UPDATE statement.
See this for more info.
UPDATE [YOUR_TABLE] SET [YOUR_FIELD] = NULL WHERE [YOUR_PRIMARY_KEY] = VALUE
Yes first you need to use delete command. Then after this insert update command then only the records will be deleted from the database. I agree that you have deleted records but its not showing because you haven't updated it.
Using Sql Server 2005
Table1
ID Name Value
001 Rajesh 90
002 Suresh 100
003 Mahesh 200
004 Virat 400
...
I want to delete the value from the table1 for the particular id
Tried Query
Delete value from table1 where id = '001'
The above query is not working.
How to make a delete query for delete the particular column
Need Query Help
There are at least two errors with your statement:
The word table will give a syntax error because it is a reserved word. You need to specify the table name of the specific table you wish to delete from.
Also you cannot write DELETE value FROM. It's just DELETE FROM. And note that it deletes the entire row, not just a single value.
A correct delete statement would look like this:
DELETE FROM table1
WHERE id = '001'
However if you want to change a single value to NULL you should use an UPDATE statement.
UPDATE table1
SET value = NULL
WHERE id = '001'
Of course this assumes that the column is nullable. If not, you'll have to fix that first. See this question for details:
Altering a column to be nullable
I think you want to set the value to null
update Table1 set value=NULL where id='001'
If I have a table with this fields:
int:id_account
int:session
string:password
Now for a login statement I run this sql UPDATE command:
UPDATE tbl_name
SET session = session + 1
WHERE id_account = 17 AND password = 'apple'
Then I check if a row was affected, and if one indeed was affected I know that the password was correct.
Next what I want to do is retrieve all the info of this affected row so I'll have the rest of the fields info.
I can use a simple SELECT statement but I'm sure I'm missing something here, there must be a neater way you gurus know, and going to tell me about (:
Besides it bothered me since the first login sql statement I ever written.
Is there any performance-wise way to combine a SELECT into an UPDATE if the UPDATE did update a row?
Or am I better leaving it simple with two statements? Atomicity isn't needed, so I might better stay away from table locks for example, no?
You should use the same WHERE statement for SELECT. It will return the modified rows, because your UPDATE did not change any columns used for lookup:
UPDATE tbl_name
SET session = session + 1
WHERE id_account = 17 AND password = 'apple';
SELECT *
FROM tbl_name
WHERE id_account = 17 AND password = 'apple';
An advice: never store passwords as plain text! Use a hash function, like this:
MD5('apple')
There is ROW_COUNT() (do read about details in the docs).
Following up by SQL is ok and simple (which is always good), but it might unnecessary stress the system.
This won't work for statements such as...
Update Table
Set Value = 'Something Else'
Where Value is Null
Select Value From Table
Where Value is Null
You would have changed the value with the update and would be unable to recover the affected records unless you stored them beforehand.
Select * Into #TempTable
From Table
Where Value is Null
Update Table
Set Value = 'Something Else'
Where Value is Null
Select Value, UniqueValue
From #TempTable TT
Join Table T
TT.UniqueValue = T.UniqueValue
If you're lucky, you may be able to join the temp table's records to a unique field within Table to verify the update. This is just one small example of why it is important to enumerate records.
You can get the effected rows by just using ##RowCount..
select top (Select ##RowCount) * from YourTable order by 1 desc