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What GRANT USAGE ON SCHEMA exactly do?
...chema within. Similiarly, GRANTing on a schema doesn't grant rights on the tables within.
If you have rights to SELECT from a table, but not the right to see it in the schema that contains it then you can't access the table.
The rights tests are done in order:
Do you have `USAGE` on the schema?...
select * vs select column
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It always pulls a tuple (except in cases where the table has been vertically segmented - broken up into columns pieces), so, to answer the question you asked, it doesn't matter from a performance perspective. However, for many other reasons, (below) you should always select ...
SQL left join vs multiple tables on FROM line?
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The old syntax, with just listing the tables, and using the WHERE clause to specify the join criteria, is being deprecated in most modern databases.
It's not just for show, the old syntax has the possibility of being ambiguous when you use both INNER and OUTER j...
What's the difference between @JoinColumn and mappedBy when using a JPA @OneToMany association
...t this entity is the owner of the relationship (that is: the corresponding table has a column with a foreign key to the referenced table), whereas the attribute mappedBy indicates that the entity in this side is the inverse of the relationship, and the owner resides in the "other" entity. This also ...
How can I return pivot table output in MySQL?
If I have a MySQL table looking something like this:
8 Answers
8
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How to find gaps in sequential numbering in mysql?
We have a database with a table whose values were imported from another system. There is an auto-increment column, and there are no duplicate values, but there are missing values. For example, running this query:
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Improving bulk insert performance in Entity framework [duplicate]
I want to insert 20000 records in a table by entity framework and it takes about 2 min. Is there any way other than using SP to improve its performance. This is my code:
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How can I join multiple SQL tables using the IDs?
I have 4 different tables that I want to join. The tables are structured with columns as follows:
4 Answers
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How to have an automatic timestamp in SQLite?
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Just declare a default value for a field:
CREATE TABLE MyTable(
ID INTEGER PRIMARY KEY,
Name TEXT,
Other STUFF,
Timestamp DATETIME DEFAULT CURRENT_TIMESTAMP
);
However, if your INSERT command explicitly sets this field to NULL, it will be set to NULL.
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quick random row selection in Postgres
I have a table in postgres that contains couple of millions of rows. I have checked on the internet and I found the following
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