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First off Im not a dba and Im fairly new to sql. These questions are probably basic SQL knowledge but here are the questions:

1. Say there are 75 million records in the database with about 100 columns. If you run a simple SELECT query with a couple where clauses, could this cause the system to "slow down" or "bog the system down"? I know hardware and usage play a part but lets just say thats not a concern.

2. How does the SELECT statement with where clauses search the database? Does it first look at the where clauses? For example: WHERE phone_number = 555555555. Does it go to the phone_number column and search ALL the phone numbers?

3. If there a more than one where clause, which where clause is processed first or are they processed simultaneously?

4. Is there a better way to search the db so these queries do not impact server performance?

Thanks for the help.

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Last Post by debasisdas
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for all your issues ,you need ot create indexes in column that is frequently bsing using in where clause of queries.

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