In MySQL, I have a comma delimited list in the following format -
'id,text,id,text,id,text,etc...'
Example -
'1001,TextFor1001,1002,TextFor1002,1003,TextFor1003,etc...'
I need to update a SQL table like this -
UPDATE mytable
SET mytable.textfor = 'TextFor1001'
WHERE mytable.id = 1001;
How can I loop through the list without having to create an UPDATE statement for each entry?
EDIT: TO EXPLAIN MY QUESTION FURTHER -
I want to read through a string that looks like this-
'1001,TextFor1001,1002,TextFor1002,1003,TextFor1003,etc...'
And perform the equivalent of having multiple update statments like this -
UPDATE mytable
SET mytable.textfor = 'TextFor1001'
WHERE mytable.id = 1001;
UPDATE mytable
SET mytable.textfor = 'TextFor1002'
WHERE mytable.id = 1002;
UPDATE mytable
SET mytable.textfor = 'TextFor1003'
WHERE mytable.id = 1003;
etc...
Is there some kind of loop I can create that can read through the string, search for the id in a table, then update the record with the corresponding text value?
The basic syntax of UPDATE query with WHERE clause is as follows:
UPDATE table_name
SET column1 = value1, column2 = value2...., columnN = valueN
WHERE [condition];
You can combine N number of conditions using AND or OR operators
Related
In a SQL table I have two columns: the first contain a path and the second contains a value.
colunm1
/path/
colunm2
12345
I need to update the first column with the value that exists in the second column. to get this result :
colunm1
/path/12456/
I tried this, but not working
update tablename p
set p.colunm1 = "/path/'colunm2'/"
You have the right idea, but the SQL you shared uses column2 as a string literal. You could use the concat to concatenate the two columns:
UPDATE tablename
SET column1 = CONCAT(column1, column2)
You have to use CONCAT
update tablename p
set p.colunm1 = CONCAT("/path/",`colunm2`,"/");
UPDATE `users` SET `D1`='hello ['firstname']' WHERE id_user >= 3
I want to update the D1 column with "hello ['firstname']"
I want to fetch firstname from another column with same row number. and the above syntax is not working out. I'm new to ṭhis. Is this possible? or not?
You can use CONCAT for that purpose, and you can so combine strings together
UPDATE `users` SET `D1`= CONCAT('hello [',`firstname`,']') WHERE id_user >= 3
Do you want to construct a string with firstname -- the column -- in it?
If so:
UPDATE users
SET D1 = CONCAT('hello', firstname')
WHERE id_user >= 3;
Is there a way in MySQL to insert a condition based on which the entire UPDATE query will be executed? I know that you can use IF or CASE within the query itself to insert different values, but I'm talking about this scenario:
IF ( condition is true ) UPDATE ...
Let's say I wanted to validate data and execute the UPDATE based on result (I know it's a bad idea and data validation should be done scripting wise, I'm just reviewing the theoretical possibilities). Like here below where I test a value against regexp to check if it's numerical value:
UPDATE executed:
IF ( "12345" REGEXP "[0-9]+" ) UPDATE table SET numdata = "12345" WHERE...;
UPDATE not executed:
IF ( "a1234" REGEXP "[0-9]+" ) UPDATE table SET numdata = "a1234" WHERE...;
Thanks,
Prez
Just put the REGEXP in your WHERE clause:
DECLARE mynumdata varchar(10) = "a1234";
UPDATE table SET numdata = mynumdata
WHERE #numdata REGEXP "[0-9]+"
AND <other update conditions>;
One way to do this would be to add the condition to the WHERE clause.
So if you originally had
UPDATE table SET numdata = "a1234" WHERE id=1
you could write this as
UPDATE table SET numdata = "a1234" WHERE id=1 AND "1234" REGEXP "[0-9]+"
I've being trying to amend the solution found in this tutorial to write an SQL query that both SELECTs and UPDATEs my table:
enter link description here
DECLARE #column1 varchar(2);
SET #column1 = (SELECT `Id`, `Url` FROM `MyTable` WHERE `Retrieved` = 0);
SELECT * FROM `MyTable` WHERE `AdId`, `Url` = #column1;
UPDATE `MyTable` SET `Retrieved` = 1 where `Id`, `Url` = #column1;
What i'm trying to achieve the following simultaneously:
SELECT Id, Url FROM MyTable WHERE Retrieved = 0
UPDATE MyTable SET Retrieved = 1
for the rows where i have SELECTed the results from
Basically, i want to select all data from ID and Url columns where the Retrieved column equals 0. I then want to set the Retrieved column to 1 for the rows i have selected.
The "normal" SQL method would be:
UPDATE MyTable
SET Retrieved = 1
WHERE id IN (SELECT Id FROM MyTable WHERE Retrieved = 0);
That does not work in MySQL. Assuming that id is unique in MyTable (a reasonable assumption in my opinion), then this does what you want:
UPDATE MyTable
SET Retrieved = 1
WHERE Retrieved = 0;
UPDATE t SET t.Retrieved=1 FROM MyTable t WHERE t.Retrieved=0
This is only updating rows, that essentially you've selected. In your case you want to update rows where the selected rows Retrieved column is equal to 0.
The other thing and maybe for readibility or you need the rows returned you can use a cte.
--first get only the records you need
WITH MyRecords_cte
AS
(
SELECT Id, URL, Retreived FROM MyTable WHERE Retreived=0
)
UPDATE MyRecords_cte SET MyRecords_cte.Retreived=1
Once you're done with the update you can return the data.
I need a SQL update statement for updating a particular field of all the rows with a string "test" to be added in the front of the existing value.
For example, if the existing value is "try" it should become "testtry".
You can use the CONCAT function to do that:
UPDATE tbl SET col=CONCAT('test',col);
If you want to get cleverer and only update columns which don't already have test prepended, try
UPDATE tbl SET col=CONCAT('test',col)
WHERE col NOT LIKE 'test%';
UPDATE tablename SET fieldname = CONCAT("test", fieldname) [WHERE ...]
Many string update functions in MySQL seems to be working like this:
If one argument is null, then concatenation or other functions return null too.
So, to update a field with null value, first set it to a non-null value, such as ''
For example:
update table set field='' where field is null;
update table set field=concat(field,' append');
That's a simple one
UPDATE YourTable SET YourColumn = CONCAT('prependedString', YourColumn);
UPDATE table_name SET Column1 = CONCAT('newtring', table_name.Column1) where 1
UPDATE table_name SET Column1 = CONCAT('newtring', table_name.Column2) where 1
UPDATE table_name SET Column1 = CONCAT('newtring', table_name.Column2, 'newtring2') where 1
We can concat same column or also other column of the table.