SQLSTATE 42804 is raised when PostgreSQL cannot implicitly cast a value to the target column or variable data type.
datatype_mismatch (SQLSTATE 42804) occurs when PostgreSQL sees incompatible data types in an assignment, comparison, or function call. Cast the value explicitly or change the target column’s type to resolve the error.
datatype_mismatch
PostgreSQL throws SQLSTATE 42804 when two data types are incompatible in an assignment, comparison, or function argument.
The server refuses to perform an unsafe implicit cast, protecting data integrity.
You must guide PostgreSQL with an explicit cast or change the schema.
A datatype_mismatch is typically triggered by inserting or updating a column with a value of another type, such as writing text into an integer column.
The error also appears when joining or comparing columns of different, non-castable types or passing mismatched arguments into a function.
First, confirm the intended data type.
If the value is correct, add an explicit cast using :: or CAST().
If the schema is wrong, alter the column to the proper type or create a domain or function overload that matches the supplied argument types.
INSERT statements often fail when CSV imports treat numbers as quoted text. Remove the quotes or cast the field to integer.
JOIN clauses break when numeric IDs are stored as text in one table.
Convert the text column to integer or cast it in the SELECT.
Define columns with the correct data type from the start, and validate all incoming data at the application layer.
Use explicit casts in ad-hoc queries and enable strict CI checks with Galaxy’s editor to catch mismatches before deployment.
Error 22P02 (invalid_text_representation) occurs when a value cannot be parsed into the target type.
Cast the literal correctly.
Error 23502 (not_null_violation) surfaces when a NULL assignment violates a constraint. Provide a non-null default or allow NULLs.
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PostgreSQL only allows safe, predefined casts.
Incompatible types like text to integer fail unless explicitly cast.
A foreign key or JOIN can compare varchar to integer, producing datatype_mismatch during query planning.
Loading data with quoted numbers makes PostgreSQL treat the value as text, conflicting with numeric columns.
Calling a function with argument types it does not accept forces PostgreSQL to attempt an implicit cast that may not exist.
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No. Most cases are fixed by adding an explicit cast in the query. Alter the table only when the column definition is wrong.
Galaxy’s AI copilot inspects schema metadata and suggests correct casts while you type, reducing mismatches before execution.
PostgreSQL already blocks unsafe casts. You can further tighten rules with domains or check constraints.
Simple casts are inexpensive. However, casting columns inside WHERE or JOIN clauses can prevent index use. Prefer schema alignment.
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