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update A
set step1_response='step2',
step1_editor='step2'
where ch_idx in (select B.ch_idx
from B
where B.check_e_done_ct=B.check_e_tot_ct
AND B.check_w_tot_ct=B.check_w_done_ct);
The result of select inside the parentheses is about 4000 rows.
The table to be updated (A) is about 90000 rows.
the command above takes forever to complete.
how can i re-write this query to get result faster?
thank you!
UPDATE a
JOIN b USING (ch_idx)
SET a.step1_response='step2',
a.step1_editor='step2'
WHERE b.check_e_done_ct = b.check_e_tot_ct
AND b.check_w_tot_ct = b.check_w_done_ct;
or maybe
UPDATE a
JOIN ( SELECT ch_idx
FROM b
WHERE b.check_e_done_ct = b.check_e_tot_ct
AND b.check_w_tot_ct = b.check_w_done_ct ) bb USING (ch_idx)
SET a.step1_response='step2',
a.step1_editor='step2';
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Can anyone help me with this? I have doubts about the below function; can I create a virtual column for this?
select as1.col,as1.col2,as1.col3 from
analytics.adjusted_sale_velocity
where
date(as1.created_datetime)=(
select
max(
date(created_datetime)
)
from
analytics.adjusted_sale_velocity
)
MySQL optimizer won't use an index once a column in the WHERE clause is wrapped with a function, date in your case.
Your query might be written a little different:
select as1.col,
as1.col2,
as1.col3
from adjusted_sale_velocity a
inner join ( select max(created_datetime) as created_datetime
from adjusted_sale_velocity
) as max_dt on left(a.created_datetime,10) = left(max_dt.created_datetime,10) ;
Try and let me know if it is faster.
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Is this SQL an atomic operation for MySQL ?
UPDATE
api_report a
JOIN
(
SELECT
id
FROM
api_report
WHERE
api_report.success_nums = 7878
) b
ON a.id = b.id
SET
a.success_nums = 4646;
Assume that I have 2 threads to execute the upper SQL, the data will be updated by 1 of the 2 thread? or by the both 2 thread concurrently?
I wrote a demo, and it seems the data is updated by only 1 of the 2 thread.
Use correct multiple-table syntax:
UPDATE api_report a
JOIN api_report b ON a.id = b.id
SET a.success_nums = 4646
WHERE b.success_nums = 7878
Attention! this query will update ALL matched rows including one which has success_nums = 7878. fiddle. If you does not need this then add more conditions to WHERE clause, for example, AND a.success_nums != 7878.
This SQL seems to be an atomic operation for MySQL.
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i want to select two columns from database id and password
and want to use those two columns data in update query
example
select id , pass from table
second update query
update table set password2=password_get_from select_query where id=id_get_from_select_query
Try something like.
update table_one as A
inner join table_two AS B on (A.id = B.id)
set A.some_column = B.some_column,
A.another_column = B.another_column
where blah
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I have 2 email tables. 1 = main email table, 2 = bounce_table.
Field email = unique in both tables.
Tasks = delete from main_email_table where email is in bounce_table.
I have no idea how to make the right call for action for this task.
I hope to get an idea how to solve this.
Thanks
check below query-
DELETE me.* FROM main_email AS me
JOIN bounce_email AS be ON me.email=be.email;
You need a DELETE with JOIN:
DELETE email_table
FROM email_table
INNER JOIN bounce_table ON bounce_table.email = email_table.email
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I am having a database with 2 columns employee and job.Job column contains character in each record.In that,I have to list the employees whose job is having last 3 characters as 'man'.I have to use only functions in SQL Query.
Use LIKE with wildcard:
SELECT *
FROM your_table
WHERE job_column_name LIKE '%man'
or using RIGHT
SELECT *
FROM your_table
WHERE RIGHT(job_column_name, 3) = 'man'
Answer For Question 4 is
SELECT *
FROM emp
WHERE SUBSTR(job,-3,3)='MAN';