Update myTable SET field = 1 (if field = 0 or if field is null) where myid = 12345;
Update myTable SET field = 0 (if field = 1) where myid = 12345;
What is the best way to transform this Pseudocode in proper SQL for Oracle and MySQL?
You could simply use the modulo like this:
UPDATE myTable SET field = (field + 1) % 2 WHERE myId = 12345;
Due to the lack of a real boolean in both DBMS you need a case statement:
update myTable
set the_column = case when the_column = 1 then 0 else 1 end
where myId = 12345;
This assumes that the column never has different values than 0 and 1
Related
I am trying to update the records in my Go project when trying to do so there is some need to update based on the conditions. I have figured out a way in mysql but that query need to be converted into gorm. Heere is the mysql query:
update table_name SET field_name1 = IF (field_name2 = 2, 1 , 0) where field_name3 = 6;
I have done this using
query := fmt.Sprintf(`UPDATE table_name SET field_name1 = IF (field_name2 = "%s", 1 , 0) where field_name3 = "%s"`, field_value1, field_value2)
s.DB.Exec(query)
I have an update query which i thought should update multiple rows in one request..
UPDATE myTable SET val = val + 1 WHERE id = "X" or "Y"
however this only seems to update X's val not Y's as well
UPDATE myTable
SET val = val + 1
WHERE id = 'X'
OR id = 'Y'
or
WHERE id in ('X', 'Y')
Your query works fine, but will ignore "Y" values because it will be evaluated as:
UPDATE myTable SET val = val + 1 WHERE id = "X" or FALSE
because "Y" will be evaluated as 0 which is false.
You have to fix your where condition to
(id = "X" or id = "Y")
I am not sure if its possible or not, Just want to know if it is. I have column plan_popular which has default value 0. Lets same i have a list :
Plan Name | plan_popular | amount
===================================
plan A 0 25.00
plan B 1 50.00
plan C 0 90.00
This is how i am doing:
$stmt = "update {CI}plans set plan_popular = 0";
$this->db->query($stmt);
$stmt2 = "update {CI}plans set plan_popular = 1 where plan_id = ?";
$this->db->query( $stmt2, array($plan_id) );
Now i have set the plan C to make. Now i want to reset it and want to make popular plan C to 1. What i am doing is running two queries, One i reset and make the plan_popular 0 and the second is get the update the plan C to 1 with there id. Is it possible in single query?
You can use an expression to determine the value to assign:
UPDATE {CI}plans
SET plan_popular = IF(plan_id = ?, 1, 0);
try this,
UPDATE {CI}plans
SET `plan_popular` = CASE `Plan Name`
WHEN 'plan C' THEN 1
ELSE 0
END
WHERE `Plan Name` IN((select `Plan Name` from {CI}plans where plan_popular=1 ) , 'plan C');
Updates can be expensive, what with manipulating locks, triggers and constraints firing, etc. In general, you want to avoid updating a field to the same value it already has. In English, if plan_id = variable and plan_popular is 0 then set it to 1 but if plan_id is any other value and plan_popular is 1 then set it to 0.
UPDATE {CI}Plans
SET plan_popular = if( plan_id = ?, 1, 0 )
where (plan_id = ? and plan_popular = 0)
or (plan_id <> ? and plan_popular = 1);
The where clause lets through only those rows that will actually be changed by the update. If this is a largish table, that can make quite a difference in response time. Logic is much less expensive than any actual operation that can performed in the database.
seems like a stupid question...
I have a mysql table where I want to modify column A to a number 0 or 1 depending on the condition of another column B
So: if( B > 500 ) A = 1 ELSE A = 0
Column A = INT
Column B = DOUBLE
How do you do something like this in sql?
Thanks,
Erik
Try the following statement,
UPDATE tableName
SET A = (B > 500)
SQLFiddle Demo
(B > 500) is a boolean arithmetic in mysql which returns 1 and 0 for true and false , respectively.
You can also use CASE for much more RDBMS friendly,
UPDATE tableName
SET A = CASE WHEN B > 500 THEN 1 ELSE 0 END
I have a flag in my database called published, I set this to 1 for a published row. My question is , is there a way to set all other rows to 0 and set a particular row to 1 with just one query.
At the moment im using:
$db->query("UPDATE my_table SET published = '0'");
$db->query("UPDATE my_table SET published = '1' WHERE id = '$id'");
UPDATE my_table SET published = IF (id = $id,1,0);
Use a CASE Statement
UPDATE my_table
SET published = CASE
WHEN id = '$id' THEN 1
ELSE 0 END
In MySQL, there's no boolean type (conditions return an integer), so this works too :
UPDATE my_table
SET published = (id = $id);
id = $id returns 0 if $id is different than id, else 1.