SQL Select, Select distinct
Select Distinct Clause
SQL Where Clause
SQL And, Or, Not
SQL Aliases
SQL Like
SQL In
SQL Between
Order By Clause
Aggregate Functions (Min, Max, Avg, Sum, Count)
Count
AVG() Syntax
SUM
MIN
MAX
Group By
HAVING Clause
SQL Insert Into
SQL Create Table
SQL Drop Table
SQL Alter Table
SQL Constraints
SQL Not Null
SQL Unique
SQL Primary Key
SQL Foreign Key
SQL Default
An index can be dropped rather simply. The most common reason to drop an index is an attempt to improve the performance. Here is the syntax to drop an index.
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DROP INDEX index_name; |
Indexes should not be used on small tables. Also, indexes should not be used on columns that contain a higher number of NULL values.
DROP INDEX IDX_LAST_NAME;
The above example drops the index IDX_last_name.
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