How to Solve Case Sensitivity Problems with Table and Column Names in PostgreSQL?

Handling Case Sensitivity in PostgreSQL Table and Column Names

PostgreSQL's treatment of table and column names depends on whether they are quoted. Unquoted identifiers (like myTable) are case-insensitive, meaning MyTable, mytable, and MYTABLE all refer to the same object. Quoted identifiers (like "MyTable") are case-sensitive.

This difference often causes problems when migrating databases, particularly from systems like MSSQL where case sensitivity might be handled differently. For instance, if a table named STD_TYPE_CODES is imported and you attempt to query it as std_type_codes, you'll get an error because PostgreSQL interprets them as distinct objects.

Solutions:

• Quoting Table Names: The simplest solution for individual queries is to quote the table name:

<code class="language-sql">SELECT * FROM "STD_TYPE_CODES";</code>

However, this is cumbersome for numerous tables.

• PostgreSQL's Implicit Downcasing: PostgreSQL automatically converts unquoted identifiers to lowercase internally. Therefore, STD_TYPE_CODES, std_type_codes, and HeLLo are all treated as "std_type_codes".

• Best Practice: Consistent Naming: To avoid future problems, consistently use unquoted, lowercase names when creating new tables and views.

• Renaming Existing Tables: For existing tables with inconsistent casing, use ALTER TABLE:

<code class="language-sql">ALTER TABLE "FOO" RENAME TO foo;</code>

• Modifying the Database Dump: If importing from another database system (e.g., MSSQL), modify the dump file to ensure all table and column names are consistently unquoted and lowercase before importing into PostgreSQL. This might involve manual editing or using specialized tools during the dump process. This is generally the most efficient approach for large migrations.

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