# sqlglot.optimizer.qualify API documentation

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# sqlglot.optimizer.qualify

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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
     7from sqlglot.optimizer.isolate_table_selects import isolate_table_selects
     8from sqlglot.optimizer.normalize_identifiers import normalize_identifiers
     9from sqlglot.optimizer.qualify_columns import (
    10    pushdown_cte_alias_columns as pushdown_cte_alias_columns_func,
    11    qualify_columns as qualify_columns_func,
    12    quote_identifiers as quote_identifiers_func,
    13    validate_qualify_columns as validate_qualify_columns_func,
    14)
    15from sqlglot.optimizer.qualify_tables import qualify_tables
    16from sqlglot.schema import Schema, ensure_schema
    17
    18
    19def qualify(
    20    expression: exp.Expression,
    21    dialect: DialectType = None,
    22    db: t.Optional[str] = None,
    23    catalog: t.Optional[str] = None,
    24    schema: t.Optional[dict | Schema] = None,
    25    expand_alias_refs: bool = True,
    26    expand_stars: bool = True,
    27    infer_schema: t.Optional[bool] = None,
    28    isolate_tables: bool = False,
    29    qualify_columns: bool = True,
    30    validate_qualify_columns: bool = True,
    31    quote_identifiers: bool = True,
    32    identify: bool = True,
    33) -> exp.Expression:
    34    """
    35    Rewrite sqlglot AST to have normalized and qualified tables and columns.
    36
    37    This step is necessary for all further SQLGlot optimizations.
    38
    39    Example:
    40        >>> import sqlglot
    41        >>> schema = {"tbl": {"col": "INT"}}
    42        >>> expression = sqlglot.parse_one("SELECT col FROM tbl")
    43        >>> qualify(expression, schema=schema).sql()
    44        'SELECT "tbl"."col" AS "col" FROM "tbl" AS "tbl"'
    45
    46    Args:
    47        expression: Expression to qualify.
    48        db: Default database name for tables.
    49        catalog: Default catalog name for tables.
    50        schema: Schema to infer column names and types.
    51        expand_alias_refs: Whether to expand references to aliases.
    52        expand_stars: Whether to expand star queries. This is a necessary step
    53            for most of the optimizer's rules to work; do not set to False unless you
    54            know what you're doing!
    55        infer_schema: Whether to infer the schema if missing.
    56        isolate_tables: Whether to isolate table selects.
    57        qualify_columns: Whether to qualify columns.
    58        validate_qualify_columns: Whether to validate columns.
    59        quote_identifiers: Whether to run the quote_identifiers step.
    60            This step is necessary to ensure correctness for case sensitive queries.
    61            But this flag is provided in case this step is performed at a later time.
    62        identify: If True, quote all identifiers, else only necessary ones.
    63
    64    Returns:
    65        The qualified expression.
    66    """
    67    schema = ensure_schema(schema, dialect=dialect)
    68    expression = normalize_identifiers(expression, dialect=dialect)
    69    expression = qualify_tables(expression, db=db, catalog=catalog, schema=schema, dialect=dialect)
    70
    71    if isolate_tables:
    72        expression = isolate_table_selects(expression, schema=schema)
    73
    74    if Dialect.get_or_raise(dialect).PREFER_CTE_ALIAS_COLUMN:
    75        expression = pushdown_cte_alias_columns_func(expression)
    76
    77    if qualify_columns:
    78        expression = qualify_columns_func(
    79            expression,
    80            schema,
    81            expand_alias_refs=expand_alias_refs,
    82            expand_stars=expand_stars,
    83            infer_schema=infer_schema,
    84        )
    85
    86    if quote_identifiers:
    87        expression = quote_identifiers_func(expression, dialect=dialect, identify=identify)
    88
    89    if validate_qualify_columns:
    90        validate_qualify_columns_func(expression)
    91
    92    return expression

def qualify( expression: sqlglot.expressions.Expression, dialect: Union[str, sqlglot.dialects.dialect.Dialect , Type[ sqlglot.dialects.dialect.Dialect ], NoneType] = None, db: Optional[str] = None, catalog: Optional[str] = None, schema: Union[dict, sqlglot.schema.Schema , NoneType] = None, expand_alias_refs: bool = True, expand_stars: bool = True, infer_schema: Optional[bool] = None, isolate_tables: bool = False, qualify_columns: bool = True, validate_qualify_columns: bool = True, quote_identifiers: bool = True, identify: bool = True) -> sqlglot.expressions.Expression: View Source

    20def qualify(
    21    expression: exp.Expression,
    22    dialect: DialectType = None,
    23    db: t.Optional[str] = None,
    24    catalog: t.Optional[str] = None,
    25    schema: t.Optional[dict | Schema] = None,
    26    expand_alias_refs: bool = True,
    27    expand_stars: bool = True,
    28    infer_schema: t.Optional[bool] = None,
    29    isolate_tables: bool = False,
    30    qualify_columns: bool = True,
    31    validate_qualify_columns: bool = True,
    32    quote_identifiers: bool = True,
    33    identify: bool = True,
    34) -> exp.Expression:
    35    """
    36    Rewrite sqlglot AST to have normalized and qualified tables and columns.
    37
    38    This step is necessary for all further SQLGlot optimizations.
    39
    40    Example:
    41        >>> import sqlglot
    42        >>> schema = {"tbl": {"col": "INT"}}
    43        >>> expression = sqlglot.parse_one("SELECT col FROM tbl")
    44        >>> qualify(expression, schema=schema).sql()
    45        'SELECT "tbl"."col" AS "col" FROM "tbl" AS "tbl"'
    46
    47    Args:
    48        expression: Expression to qualify.
    49        db: Default database name for tables.
    50        catalog: Default catalog name for tables.
    51        schema: Schema to infer column names and types.
    52        expand_alias_refs: Whether to expand references to aliases.
    53        expand_stars: Whether to expand star queries. This is a necessary step
    54            for most of the optimizer's rules to work; do not set to False unless you
    55            know what you're doing!
    56        infer_schema: Whether to infer the schema if missing.
    57        isolate_tables: Whether to isolate table selects.
    58        qualify_columns: Whether to qualify columns.
    59        validate_qualify_columns: Whether to validate columns.
    60        quote_identifiers: Whether to run the quote_identifiers step.
    61            This step is necessary to ensure correctness for case sensitive queries.
    62            But this flag is provided in case this step is performed at a later time.
    63        identify: If True, quote all identifiers, else only necessary ones.
    64
    65    Returns:
    66        The qualified expression.
    67    """
    68    schema = ensure_schema(schema, dialect=dialect)
    69    expression = normalize_identifiers(expression, dialect=dialect)
    70    expression = qualify_tables(expression, db=db, catalog=catalog, schema=schema, dialect=dialect)
    71
    72    if isolate_tables:
    73        expression = isolate_table_selects(expression, schema=schema)
    74
    75    if Dialect.get_or_raise(dialect).PREFER_CTE_ALIAS_COLUMN:
    76        expression = pushdown_cte_alias_columns_func(expression)
    77
    78    if qualify_columns:
    79        expression = qualify_columns_func(
    80            expression,
    81            schema,
    82            expand_alias_refs=expand_alias_refs,
    83            expand_stars=expand_stars,
    84            infer_schema=infer_schema,
    85        )
    86
    87    if quote_identifiers:
    88        expression = quote_identifiers_func(expression, dialect=dialect, identify=identify)
    89
    90    if validate_qualify_columns:
    91        validate_qualify_columns_func(expression)
    92
    93    return expression

Rewrite sqlglot AST to have normalized and qualified tables and columns.

This step is necessary for all further SQLGlot optimizations.

###### Example:

>     >>> import sqlglot
>     >>> schema = {"tbl": {"col": "INT"}}
>     >>> expression = sqlglot.parse_one("SELECT col FROM tbl")
>     >>> qualify(expression, schema=schema).sql()
>     'SELECT "tbl"."col" AS "col" FROM "tbl" AS "tbl"'

###### Arguments:

- expression: Expression to qualify.
- db: Default database name for tables.
- catalog: Default catalog name for tables.
- schema: Schema to infer column names and types.
- expand_alias_refs: Whether to expand references to aliases.
- expand_stars: Whether to expand star queries. This is a necessary step for most of the optimizer's rules to work; do not set to False unless you know what you're doing!
- infer_schema: Whether to infer the schema if missing.
- isolate_tables: Whether to isolate table selects.
- qualify_columns: Whether to qualify columns.
- validate_qualify_columns: Whether to validate columns.
- quote_identifiers: Whether to run the quote_identifiers step. This step is necessary to ensure correctness for case sensitive queries. But this flag is provided in case this step is performed at a later time.
- identify: If True, quote all identifiers, else only necessary ones.

###### Returns:

> The qualified expression.