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How to drop columns using Rails migration
What's the syntax for dropping a database table column through a Rails migration?
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How do you rename a table in SQLite 3.0?
How do you rename a table in SQLite 3.0?
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In MySQL queries, why use join instead of where?
It seems like to combine two or more tables, we can either use join or where. What are the advantages of one over the other?
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SQL, Postgres OIDs, What are they and why are they useful?
I am looking at some PostgreSQL table creation and I stumbled upon this:
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How do SQL EXISTS statements work?
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For 'each' row from Suppliers, check if there 'exists' a row in the Order table that meets the condition Suppliers.supplier_id (this comes from Outer query current 'row') = Orders.supplier_id. When you find the first matching row, stop right there - the WHERE EXISTS has been satisfied.
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MySQL error: key specification without a key length
I have a table with a primary key that is a varchar(255). Some cases have arisen where 255 characters isn't enough. I tried changing the field to a text, but I get the following error:
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CSS vertical alignment text inside li
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Define the parent with display: table and the element itself with vertical-align: middle and display: table-cell.
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How to get Last record from Sqlite?
I have a one table question_table and one ImageButton ( Back ). I need to get the last inserted record from the database after clicking on the Back .
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How do MySQL indexes work?
...ically, how can they return the data requested without scanning the entire table?
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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!
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