Let's just say I have a table called TABLE_NAME that looks like this:
id | name | changeme
------------------------
1 | One | 1
2 | Two | 0
3 | Three | 1
4 | Four | 0
5 | Five | 0
Is there an SQL statement I can run on this to change every changeme entry to '0'?
do you mean?
UPDATE TABLE_NAME SET changeme = 0
update TABLE_NAME set changeme = 0 where changeme = 1
update TABLE_NAME SET changeme="0" WHERE id IN (1,3,4)
if you want to update data where ID is specific like 1,3, and 4
This works for single table
UPDATE table_name
SET field_name = replace(same_field_name, 'unwanted_text', 'wanted_text')
Related
I want to have the column "CurrentCapacity" to be the SUM of all references specific column.
Lets say there are three rows in SecTable which all have FirstTableID = 1. Size values are 1, 1 and 3.
The row in FirstTable which have ID = 1 should now have a value of 5 in the CurrentCapacity column.
How can I make this and how to do automatically on insert, update and delete?
Thanks!
FirstTable
+----+-------------+-------------------------+
| ID | MaxCapacity | CurrentCapacity |
+----+-------------+-------------------------+
| 1 | 5 | 0 (desired result = 5) |
+----+-------------+-------------------------+
| 2 | 5 | 0 |
+----+-------------+-------------------------+
| 3 | 5 | 0 |
+----+-------------+-------------------------+
SecTable
+----+-------------------+------+
| ID | FirstTableID (FK) | Size |
+----+-------------------+------+
| 1 | 1 | 2 |
+----+-------------------+------+
| 2 | 1 | 3 |
+----+-------------------+------+
In general, a view is a better solution than trying to keep a calculated column up-to-date. For your example, you could use this:
CREATE VIEW capacity AS
SELECT f.ID, f.MaxCapacity, COALESCE(SUM(s.Size), 0) AS CurrentCapacity
FROM FirstTable f
LEFT JOIN SecTable s ON s.FirstTableID = f.ID
GROUP BY f.ID, f.MaxCapacity
Then you can simply
SELECT *
FROM capacity
to get the results you desire. For your sample data:
ID MaxCapacity CurrentCapacity
1 5 5
2 5 0
3 5 0
Demo on SQLFiddle
Got this question to work with this trigger:
CREATE TRIGGER UpdateCurrentCapacity
ON SecTable
AFTER INSERT, UPDATE, DELETE
AS
BEGIN
SET NOCOUNT ON
DECLARE #Iteration INT
SET #Iteration = 1
WHILE #Iteration <= 100
BEGIN
UPDATE FirstTable SET FirstTable.CurrentCapacity = (SELECT COALESCE(SUM(SecTable.Size),0) FROM SecTable WHERE FirstTableID = #Iteration) WHERE ID = #Iteration;
SET #Iteration = #Iteration + 1
END
END
GO
Personally, I would not use a trigger either or store CurrentCapacity as a value since it breaks Normalization rules for database design. You have a relation and can already get the results by creating a view or setting CurrentCapacity to a calculated column.
Your view can look like this:
SELECT Id, MaxCapacity, ISNULL(O.SumSize,0) AS CurrentCapacity
FROM dbo.FirstTable FT
OUTER APPLY
(
SELECT ST.FirstTableId, SUM(ST.Size) as SumSize FROM SecTable ST
WHERE ST.FirstTableId = FT.Id
GROUP BY ST.FirstTableId
) O
Sure, you could fire a proc every time a row is updated/inserted or deleted in the second table and recalculate the column, but you might as well calculate it on the fly. If it's not required to have the column accurate, you can have a job update the values every X hours. You could combine this with your view to have both a "live" and "cached" version of the capacity data.
I have a table with md5 sums for files and use the following query to find the files which exist in one hashing-run and not in the other (oldt vs newt):
SELECT *
FROM md5_sums as oldt
WHERE NOT EXISTS (SELECT *
FROM md5_sums as newt
WHERE oldt.file = newt.file
and oldt.relpath = newt.relpath
and newt.starttime = 234)
and oldt.starttime = 123
now I want to put a flag in an extra column with an update clause, like
update md5_sums
set only_in_old = 'X'
where
and there I want a reference to the upper query as subquery, but i cannot find a proper way. Is there a possibility to use the results from the upper query for the where clause from the update-query?
(I added now some Table Screenshots with simple Table Data)
Table Description
Table Data before UPDATE
desired Table Data after UPDATE
SQLite does not support aliasing the updated table.
In your case you don't need that.
You can use the table's name md5_sums inside the subquery since you aliased the table of the SELECT statement as newt.
UPDATE md5_sums
SET only_in_old = 'X'
WHERE NOT EXISTS (
SELECT 1 FROM md5_sums AS newt
WHERE md5_sums.file = newt.file
AND md5_sums.relpath = newt.relpath
AND newt.starttime = 234
)
AND starttime = 123
See the demo.
Results:
| file | relpath | starttime | only_in_old |
| ------- | -------- | --------- | ----------- |
| abc.txt | /var/tmp | 123 | |
| abc.txt | /var/tmp | 234 | |
| def.txt | /tmp | 123 | X |
| xyz.txt | /tmp | 234 | |
I hope this helps you in converting the select statement into an update statement,
UPDATE md5_sums
SET only_in_old = 'X'
WHERE NOT EXISTS (SELECT *
FROM md5_sums newt
WHERE file = newt.file
and relpath = newt.relpath
and newt.starttime = 1551085649.7764235)
and starttime = 1551085580.009046
I have two tables
Travel Table
tid | tname | countryid | status
1 | a | 1 |
PassengerTravel
tid | passengerid
1 | 1
1 | 2
i want update status column in table 1 if insert in passenger Travel table
and update status column if print the travel application for them
Can you do with your code ?
the first one it can use trigger to manage it.
the second you print with your application right ?
why not let the code to update this.
Lets say I have a table : "MyTable" and I have two columns in it : "val" and "val_new".
Now I want to insert new value into "val_new" but if the values are equal('val' and 'val_new') I want to insert NULL instead.
----------------------
| id | val | val_new |
----------------------
| 1 | 5 | NULL |
----------------------
| 2 | 6 | NULL |
----------------------
Lets have this table for example.
Now :
UPDATE myTable mt
SET mt.val_new = '5'
WHERE mt.id = '1';
I want the value of val_new to remain NULL or be updated to NULL instead of '5'.
EDIT:
I want to UPDATE existing values not INSERTING new rows.
Your question seems a bit confusing in some parts. The way your word it seems like a new row is to be created but it also seems like you want to update it? Hopefully this is what you wanted :)
UPDATE testVal Set val_new = CASE WHEN val = 5 THEN NULL ELSE 5 END
testVal is your table. If you wanted to use a different number just replace both 5 with the number of your choice. I used 5 because you used it in your example.
You need not have to insert a record rather you will have to update the existing one. If you run your insert command a new record will be created. So you table will have
----------------
|val | val_new |
----------------
| 5 | NULL |
----------------
| 6 | NULL |
----------------
| | | <-- if val = val_new
----------------
| | 6 | <==if val<> val_new.
I guess you dont need this output. So the best option is to update the columns.
You can use case statement,
update <yourtable>
set val_new =case
when val_new= val then
NULL
else val_new
end
How would I go about updating a table by using another table so it puts in the new data and if it doesnt match on an id it adds the new id and the data with it. My original table i much bigger than the new table that will update it. and the new table has a few ids that aren't in the old table but need to be added.
for example I have:
Table being updated-
+-------------------+
| Original Table |
+-------------------+
| ID | Initials |
|------+------------|
| 1 | ABC |
| 2 | DEF |
| 3 | GHI |
and...
the table I'm pulling data from to update the other table-
+-------------------+
| New Table |
+-------------------+
| ID | Initials |
|------+------------|
| 1 | XZY |
| 2 | QRS |
| 3 | GHI |
| 4 | ABC |
then I want my Original table to get its values that match up to be updated by the new table if they have changed, and add any new ID rows if they aren't in the original table so in this example it would look like the New Table.
+-------------------+
| Original Table |
+-------------------+
| ID | Initials |
|------+------------|
| 1 | XZY |
| 2 | QRS |
| 3 | GHI |
| 4 | ABC |
You can use MERGE statement to put this UPSERT operation in one statement but there are issues with merge statement I would split it into two Statements, UPDATE and INSERT
UPDATE
UPDATE O
SET O.Initials = N.Initials
FROM Original_Table O INNER JOIN New_Table N
ON O.ID = N.ID
INSERT
INSERT INTO Original_Table (ID , Initials)
SELECT ID , Initials
FROM New_Table
WHERE NOT EXISTS ( SELECT 1
FROM Original_Table
WHERE ID = Original_Table.ID)
Important Note
Reason why I suggested to avoid using merge statement read this article Use Caution with SQL Server's MERGE Statement by Aaron Bertrand
You need to use the MERGE statement for this:
MERGE original_table AS Target
USING updated_table as Source
ON original_table.id = updated_table.id
WHEN MATCHED THEN UPDATE SET Target.Initials = Source.Initials
WHEN NOT MATCHED THEN INSERT(id, Initials) VALUES(Source.id, Source.Initials);
You have not specified, what happens in case the valuesin original table are not found in the updated one. But, just in case, you can add this to remove them from original table:
WHEN NOT MATCHED BY SOURCE
THEN DELETE
if you can use loop in PHP and go through all tables and copy one by one to another table.
another option
DECLARE #COUT INT
SET #COUT = SELECT COUNT(*) FROM New_Table
WHILE (true)
BEGIN
IF #COUT = 0
BREAK;
SET #COUT = #COUT - 1
DECLARE #id INT
DECLARE #ini VARCHAR(20)
SET #id = (SELECT id FROM New_Table);
SET #ini = (SELECT Initials FROM New_Table);
IF (SELECT COUNT(*) FROM Original_Table WHERE id=#id ) > 0
UPDATE SET ID = #id,Initials = #ini FROM Original_Table WHERE id = #id;
insert into Original_Table values(#id,#ini);
END
GO