This shows you the differences between two versions of the page.
| Both sides previous revision Previous revision Next revision | Previous revision | ||
|
admin:indexing:concepts:joins [2011/03/17 21:40] deb |
admin:indexing:concepts:joins [2016/06/28 22:38] (current) |
||
|---|---|---|---|
| Line 3: | Line 3: | ||
| {{page>:top_add&nofooter&noeditbtn}} | {{page>:top_add&nofooter&noeditbtn}} | ||
| - | ====== Administration: Indexing Strategies ====== | + | ====== Administration: Omnidex Indexing ====== |
| ===== Indexing Concepts ===== | ===== Indexing Concepts ===== | ||
| Line 24: | Line 24: | ||
| It is common to join to a table so that criteria can be processed against it. The following example shows a join that returns columns from the INDIVIDUALS table to the user, but also joins to the HOUSEHOLDS and STATES tables to process criteria. These joins are Qualification Joins since no data is returned to the user from these tables. | It is common to join to a table so that criteria can be processed against it. The following example shows a join that returns columns from the INDIVIDUALS table to the user, but also joins to the HOUSEHOLDS and STATES tables to process criteria. These joins are Qualification Joins since no data is returned to the user from these tables. | ||
| - | <code sql> | + | <code> |
| select I.NAME, I.PHONE | select I.NAME, I.PHONE | ||
| Line 44: | Line 44: | ||
| Some tables are joined so that data can be returned to the user. The following example shows a join that returns columns from the INDIVIDUALS, HOUSEHOLDS and STATES tables. These joins are Retrieval Joins since data is returned from these tables to the user. | Some tables are joined so that data can be returned to the user. The following example shows a join that returns columns from the INDIVIDUALS, HOUSEHOLDS and STATES tables. These joins are Retrieval Joins since data is returned from these tables to the user. | ||
| - | <code sql> | + | <code> |
| select I.NAME, H.ADDRESS, H.CITY, H.STATE, I.PHONE, S.TAX_RATE | select I.NAME, H.ADDRESS, H.CITY, H.STATE, I.PHONE, S.TAX_RATE | ||
| Line 62: | Line 62: | ||
| If the query retrieved a large portion of each table, indexing would be less helpful. This query below retrieves all rows in the United States, which probably comprises a large percentage of this database. | If the query retrieved a large portion of each table, indexing would be less helpful. This query below retrieves all rows in the United States, which probably comprises a large percentage of this database. | ||
| - | <code sql> | + | <code> |
| select I.NAME, H.ADDRESS, H.CITY, H.STATE, I.PHONE, S.TAX_RATE | select I.NAME, H.ADDRESS, H.CITY, H.STATE, I.PHONE, S.TAX_RATE | ||