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...foo(x) return x^2 end
foo = function(x) return x^2 end
Table
所谓Table其实就是一个Key Value的数据结构，它很像Javascript中的Object，或是PHP中的数组，在别的语言里叫Dict或Map，Table长成这个样子：
1
haoel = {name=...
Adding a column to an existing table in a Rails migration
...e the add_column line completely (that code is trying to add a column to a table, before the table has been created, and your table creation code has already been updated to include a t.string :email anyway).
share
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PostgreSQL - how to quickly drop a user with existing privileges
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Doing: CREATE TABLE foo(bar SERIAL); ALTER TABLE foo OWNER TO postgres; CREATE USER testuser; GRANT ALL ON foo TO testuser; DROP USER testuser gave the error messages: ERROR: role "testuser" cannot be dropped because some objects depend...
ALTER TABLE, set null in not null column, PostgreSQL 9.1
I have a table with not null column, How to set a null value in this column as default?
4 Answers
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How do I execute a stored procedure once for each row returned by query?
... way. I pass it user_id and it does it's thing. I want to run a query on a table and then for each user_id I find run the stored procedure once on that user_id
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SQL Server : Columns to Rows
...nto rows:
select id, entityId,
indicatorname,
indicatorvalue
from yourtable
unpivot
(
indicatorvalue
for indicatorname in (Indicator1, Indicator2, Indicator3)
) unpiv;
Note, the datatypes of the columns you are unpivoting must be the same so you might have to convert the datatypes prior t...
SQL Server NOLOCK and joins
...argument, just your original question.
Yes, you need WITH(NOLOCK) on each table of the join. No, your queries are not the same.
Try this exercise. Begin a transaction and insert a row into table1 and table2. Don't commit or rollback the transaction yet. At this point your first query will retu...
MySql Table Insert if not exist otherwise update
...ould not change. You do need to include all of the other columns from your table. You can use the VALUES() function to make sure the proper values are used when updating the other columns.
Here is your update re-written using the proper INSERT ... ON DUPLICATE KEY UPDATE syntax for MySQL:
INSERT I...
Simplest way to do a recursive self-join?
...is the simplest way of doing a recursive self-join in SQL Server? I have a table like this:
5 Answers
...
sql server invalid object name - but tables are listed in SSMS tables list
.... However the SSMS intellisense does not recognize more than half of the tables which have been created.
16 Answers
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