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How can I get column names from a table in Oracle?
...he database to get the column names , not to be confused with data in the table. For example, if I have a table named EVENT_LOG that contains eventID , eventType , eventDesc , and eventTime , then I would want to retrieve those field names from the query and nothing else.
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MySQL - Rows to Columns
...e of terms that I'll use for the rest of this post. This will be the base table:
select * from history;
+--------+----------+-----------+
| hostid | itemname | itemvalue |
+--------+----------+-----------+
| 1 | A | 10 |
| 1 | B | 3 |
| 2 | A | ...
Adding an identity to an existing column
I need to change the primary key of a table to an identity column, and there's already a number of rows in table.
19 Answe...
Explicit vs implicit SQL joins
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Personally I prefer the join syntax as its makes it clearer that the tables are joined and how they are joined. Try compare larger SQL queries where you selecting from 8 different tables and you have lots of filtering in the where. By using join syntax you separate out the parts where the tabl...
How does a hash table work?
I'm looking for an explanation of how a hash table works - in plain English for a simpleton like me!
15 Answers
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How to convert an entire MySQL database characterset and collation to UTF-8?
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Use the ALTER DATABASE and ALTER TABLE commands.
ALTER DATABASE databasename CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
ALTER TABLE tablename CONVERT TO CHARACTER SET utf8mb4 COLLATE utf8mb4_unicode_ci;
Or if you're still on MySQL 5.5.2 or older wh...
This Row already belongs to another table error when trying to add rows?
I have a DataTable which has some rows and I am using the select to filter the rows to get a collection of DataRows which I then loop through using foreach and add it to another DataTable, but it is giving me the error "This Row already belongs to another table". Here is the code:
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How can I list ALL grants a user received?
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If you want more than just direct table grants (e.g., grants via roles, system privileges such as select any table, etc.), here are some additional queries:
System privileges for a user:
SELECT PRIVILEGE
FROM sys.dba_sys_privs
WHERE grantee = <theUser...
ALTER TABLE without locking the table?
When doing an ALTER TABLE statement in MySQL, the whole table is read-locked (allowing concurrent reads, but prohibiting concurrent writes) for the duration of the statement. If it's a big table, INSERT or UPDATE statements could be blocked for a looooong time. Is there a way to do a "hot alter", li...
How to create a DataTable in C# and how to add rows?
How do create a DataTable in C#?
13 Answers
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