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How to Access JDBC ResultSet Columns with Table Aliases?

Patricia Arquette
Release: 2024-12-30 16:06:13
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How to Access JDBC ResultSet Columns with Table Aliases?

JDBC ResultSet Columns with Table Aliases

When executing a query like "SELECT * from table1 a, table2 b where (WHATEVER)", accessing data with "resultSet.getString("a.columnName")" or "resultSet.getString("b.columnName")" fails.

The JDBC API does not explicitly address this scenario, leaving it vendor-dependent. However, you can resolve this issue by:

Option 1: Column Renaming

Name columns differently in the query using aliases, such as:

SELECT
    a.columnName as columnNameA,
    b.columnName as columnNameB,
    ...
from table1 a, table2 b where (WHATEVER)
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Then reference these aliases in your Java code:

resultSet.getString("columnNameA");
resultSet.getString("columnNameB");
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Option 2: Column Position

Refer to columns by position in the result set:

resultSet.getString(1);
resultSet.getString(2);
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Note that JDBC uses one-based indexing, starting from 1 for the first column.

For safety and maintainability, Option 1 (Column Renaming) is recommended. If a query's column order changes, your code will break silently when accessing the wrong columns. By contrast, changing column names will raise a "no such column" exception, alerting you to the issue.

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