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I see people write SQL query, for example,
select count(*)
from xxx_table
where yyy='abc'
limit 0
wondering what means limit 0 here? Referred some documents and discussions and still feel confused.
291
If you want to limit the range of an integer column you can use a check constraint: create table some_table ( phone_number integer not null check (phone_number between 0 and 9999999999) );
The LIMIT clause is used in the SELECT statement to constrain the number of rows in a result set. The LIMIT clause accepts one or two arguments. The values of both arguments must be zero or positive integer constants.
SELECT column_list FROM table_name ORDER BY expression LIMIT n-1, 1; In this syntax, the LIMIT n-1, 1 clause returns 1 row that starts at the row n. For example, the following query returns the employee information who has the second-highest income: SELECT emp_name, city, income FROM employees.
This LIMIT clause would return 3 records in the result set with an offset of 1. What this means is that the SELECT statement would skip the first record that would normally be returned and instead return the second, third, and fourth records.
As per MySQL docs:
LIMIT 0 quickly returns an empty set. This can be useful for checking the validity of a query. It can also be employed to obtain the types of the result columns if you are using a MySQL API that makes result set metadata available.
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