Writing SQL Statements
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When you create a report, you usually want to display data without affecting the data itself. The SQL statement that you construct to retrieve the data will therefore usually be a SELECT statement. The following table describes the common types of SELECT queries.
Query type | Description | Example |
Simple SELECT | Selects specified fields (columns) from one or more tables. |
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Totals | Groups data at table level or at group level; may summarize data with SQL aggregate functions. |
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INNER JOIN | Joins two tables on a field that both have in common; results include only records (rows) for which both tables share a common value in the joined field. |
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LEFT OUTER JOIN and RIGHT OUTER JOIN | Joins two tables on a field that both have in common; results include all records from one table and only records from the other table where the joined fields are equal. Useful for finding unmatched records in two tables. |
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UNION | Returns combined result set including records from two tables that have common fields. |
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CROSSTAB | Summarizes tabular data in a columnar format. |
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TOP N, TOP N PERCENT | Retrieves the top n or n percent of values, based on the order in which the records are sorted. |
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PARAMETER | Prompts user to enter parameters for query that are used to restrict the result set. |
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For more information about designing SQL statements, search the Microsoft Access Help index for "SQL statements."