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How are virtual functions and vtable implemented?
...ons in C++":
Whenever a program has a virtual function declared, a v - table is constructed for the class. The v-table consists of addresses to the virtual functions for classes that contain one or more virtual functions. The object of the class containing the virtual function contains a virtual...
What should I name a table that maps two tables together? [closed]
Let's say I have two tables:
24 Answers
24
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SQL Server insert if not exists best practice
I have a Competitions results table which holds team member's names and their ranking on one hand.
8 Answers
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How to get the next auto-increment id in mysql
How to get the next id in mysql to insert it in the table
19 Answers
19
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Best way to do multi-row insert in Oracle?
...
In Oracle, to insert multiple rows into table t with columns col1, col2 and col3 you can use the following syntax:
INSERT ALL
INTO t (col1, col2, col3) VALUES ('val1_1', 'val1_2', 'val1_3')
INTO t (col1, col2, col3) VALUES ('val2_1', 'val2_2', 'val2_3')
I...
How can I check MySQL engine type for a specific table?
My MySQL database contains several tables using different storage engines
(specifically myisam and innodb). How can I find out which tables are
using which engine?
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Create unique constraint with null columns
I have a table with this layout:
4 Answers
4
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How to check if a Constraint exists in Sql server?
...QUE, PRIMARY KEY, and/or FOREIGN KEY
SELECT *
FROM INFORMATION_SCHEMA.TABLE_CONSTRAINTS
WHERE CONSTRAINT_NAME='XYZ'
--Returns one row for each FOREIGN KEY constrain
SELECT *
FROM INFORMATION_SCHEMA.REFERENTIAL_CONSTRAINTS
WHERE CONSTRAINT_NAME='XYZ'
--Returns one row for eac...
Surrogate vs. natural/business keys [closed]
...lled as such. It is nothing more than a NOT NULL UNIQUE constraint, and a table can have more than one.
If you use a surrogate key, you still want a business key to ensure uniqueness according to the business rules.
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Replacing NAs with latest non-NA value
In a data.frame (or data.table), I would like to "fill forward" NAs with the closest previous non-NA value. A simple example, using vectors (instead of a data.frame ) is the following:
...