# sqlglot.optimizer.normalize_identifiers API documentation

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# sqlglot.optimizer.normalize_identifiers

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     1from __future__ import annotations
     2
     3import typing as t
     4
     5from sqlglot import exp
     6from sqlglot.dialects.dialect import Dialect, DialectType
     7
     8if t.TYPE_CHECKING:
     9    from sqlglot._typing import E
    10
    11
    12@t.overload
    13def normalize_identifiers(expression: E, dialect: DialectType = None) -> E:
    14    ...
    15
    16
    17@t.overload
    18def normalize_identifiers(expression: str, dialect: DialectType = None) -> exp.Identifier:
    19    ...
    20
    21
    22def normalize_identifiers(expression, dialect=None):
    23    """
    24    Normalize all unquoted identifiers to either lower or upper case, depending
    25    on the dialect. This essentially makes those identifiers case-insensitive.
    26
    27    It's possible to make this a no-op by adding a special comment next to the
    28    identifier of interest:
    29
    30        SELECT a /* sqlglot.meta case_sensitive */ FROM table
    31
    32    In this example, the identifier `a` will not be normalized.
    33
    34    Note:
    35        Some dialects (e.g. BigQuery) treat identifiers as case-insensitive even
    36        when they're quoted, so in these cases all identifiers are normalized.
    37
    38    Example:
    39        >>> import sqlglot
    40        >>> expression = sqlglot.parse_one('SELECT Bar.A AS A FROM "Foo".Bar')
    41        >>> normalize_identifiers(expression).sql()
    42        'SELECT bar.a AS a FROM "Foo".bar'
    43        >>> normalize_identifiers("foo", dialect="snowflake").sql(dialect="snowflake")
    44        'FOO'
    45
    46    Args:
    47        expression: The expression to transform.
    48        dialect: The dialect to use in order to decide how to normalize identifiers.
    49
    50    Returns:
    51        The transformed expression.
    52    """
    53    dialect = Dialect.get_or_raise(dialect)
    54
    55    if isinstance(expression, str):
    56        expression = exp.parse_identifier(expression, dialect=dialect)
    57
    58    def _normalize(node: E) -> E:
    59        if not node.meta.get("case_sensitive"):
    60            exp.replace_children(node, _normalize)
    61            node = dialect.normalize_identifier(node)
    62        return node
    63
    64    return _normalize(expression)

def normalize_identifiers(expression, dialect=None): View Source

    23def normalize_identifiers(expression, dialect=None):
    24    """
    25    Normalize all unquoted identifiers to either lower or upper case, depending
    26    on the dialect. This essentially makes those identifiers case-insensitive.
    27
    28    It's possible to make this a no-op by adding a special comment next to the
    29    identifier of interest:
    30
    31        SELECT a /* sqlglot.meta case_sensitive */ FROM table
    32
    33    In this example, the identifier `a` will not be normalized.
    34
    35    Note:
    36        Some dialects (e.g. BigQuery) treat identifiers as case-insensitive even
    37        when they're quoted, so in these cases all identifiers are normalized.
    38
    39    Example:
    40        >>> import sqlglot
    41        >>> expression = sqlglot.parse_one('SELECT Bar.A AS A FROM "Foo".Bar')
    42        >>> normalize_identifiers(expression).sql()
    43        'SELECT bar.a AS a FROM "Foo".bar'
    44        >>> normalize_identifiers("foo", dialect="snowflake").sql(dialect="snowflake")
    45        'FOO'
    46
    47    Args:
    48        expression: The expression to transform.
    49        dialect: The dialect to use in order to decide how to normalize identifiers.
    50
    51    Returns:
    52        The transformed expression.
    53    """
    54    dialect = Dialect.get_or_raise(dialect)
    55
    56    if isinstance(expression, str):
    57        expression = exp.parse_identifier(expression, dialect=dialect)
    58
    59    def _normalize(node: E) -> E:
    60        if not node.meta.get("case_sensitive"):
    61            exp.replace_children(node, _normalize)
    62            node = dialect.normalize_identifier(node)
    63        return node
    64
    65    return _normalize(expression)

Normalize all unquoted identifiers to either lower or upper case, depending on the dialect. This essentially makes those identifiers case-insensitive.

It's possible to make this a no-op by adding a special comment next to the identifier of interest:

    SELECT a /* sqlglot.meta case_sensitive */ FROM table

In this example, the identifier `a` will not be normalized.

###### Note:

> Some dialects (e.g. BigQuery) treat identifiers as case-insensitive even when they're quoted, so in these cases all identifiers are normalized.

###### Example:

>     >>> import sqlglot
>     >>> expression = sqlglot.parse_one('SELECT Bar.A AS A FROM "Foo".Bar')
>     >>> normalize_identifiers(expression).sql()
>     'SELECT bar.a AS a FROM "Foo".bar'
>     >>> normalize_identifiers("foo", dialect="snowflake").sql(dialect="snowflake")
>     'FOO'

###### Arguments:

- expression: The expression to transform.
- dialect: The dialect to use in order to decide how to normalize identifiers.

###### Returns:

> The transformed expression.