Category Archives: Oracle

INDEXES

INDEXES

Index is typically a listing of keywords accompanied by the location of information on a subject. We can create indexes explicitly to speed up SQL statement execution on a table. The index points directly to the location of the rows containing the value. Continue reading

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WALKUP TREES or Hierarchy AND INLINE VIEW

WALKUP TREES (Hierarchy) AND INLINE VIEW 

WALKUP TREES
Using hierarchical queries, you can retrieve data based on a natural hierarchical relationship between rows in a table. However, where a hierarchical relationship exists between the rows of a table, a process called tree walking enables the hierarchy to be constructed. Continue reading

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JOINS

JOINS

The purpose of a join is to combine the data across tables.

  • A join is actually performed by the where clause which combines the specified rows of tables.
  • If a join involves in more than two tables then oracle joins first two tables based on the joins condition and then compares the result with the next table and so on. Continue reading

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