Module expr

Expand description

Type-safe SQL expression system.

This module provides a type-safe wrapper around SQL expressions that tracks:

The SQL data type of the expression
Whether the expression can be NULL
Whether the expression is an aggregate or scalar

§Example

use drizzle_core::expr::*;

// Type-safe comparisons
let condition = eq(users.id, 10);  // OK: Int == Int
// let bad = eq(users.id, "hello"); // ERROR: Int != Text

// Type-safe arithmetic
let total = users.price + users.tax;  // OK: both Numeric
// let bad = users.name + users.id;   // ERROR: Text + Int

Structs§

Agg: Marker indicating an aggregate expression (COUNT, SUM, etc.).
AliasedExpr: An expression aliased with AS "name".
AllAgg: Status indicating all selected expressions are aggregate.
AllScalar: Status indicating all selected expressions are scalar (non-aggregate).
CaseBuilder: Builder state after at least one WHEN branch has been added.
CaseInit: Builder state before the first WHEN branch.
Excluded: Wraps a column to reference its value from the proposed insert row (the EXCLUDED row in ON CONFLICT DO UPDATE SET).
MixedAgg: Status indicating a mix of scalar and aggregate expressions.
NonNull: Marker indicating an expression cannot be NULL.
Null: Marker indicating an expression can be NULL.
SQLExpr: A SQL expression that carries type information.
Scalar: Marker indicating a scalar (non-aggregate) expression.
WindowFnExpr: A window function expression that is not yet valid SQL.
WindowSpec: Builder for a window specification (the content inside OVER (...)).

Enums§

FrameBound: Specifies a bound for a window frame (ROWS/RANGE BETWEEN).

Traits§

AggOr: Combine aggregate kinds: if either input is Agg, output is Agg.
AggToStatus: Convert an AggregateKind to an initial AggStatus.
AggregateKind: Marker trait for expression aggregation state.
AggregatePolicy: Dialect-specific aggregate output mapping.
AliasExt: Extension trait providing .alias() method syntax on any expression.
BooleanAggregatePolicy
CastTarget: Input accepted by cast.
CastTypePolicy: Additional cast safety policy by dialect.
CharLengthPolicy: Dialect-aware function name for CHAR_LENGTH.
CombineAggStatus: Combine two aggregate statuses.
ComparisonOperand: Type-safe operand for comparison functions.
CountPolicy
DateTruncPolicy
DefaultCastTypeName: Default SQL cast type name for a type marker.
Expr: An expression in SQL with an associated data type.
ExprExt: Extension trait providing method-based comparisons for any Expr type.
FloatPolicy
HasAggStatus: Extract the aggregate status of a type that appears in a SELECT list.
InSubqueryLhs: Left-hand side of an IN (subquery) expression.
LengthPolicy
NullAnd: Combine nullability for COALESCE-style fallback behavior.
NullOr: Combine nullability: if either input is nullable, output is nullable.
Nullability: Marker trait for nullability state.
PostgresAggregateSupport
PostgresDateTimeSupport
PostgresMathSupport
PostgresNullSupport: Marker trait for dialects that support GREATEST/LEAST (PostgreSQL).
PostgresStringSupport
RandomPolicy: Dialect-specific return type for RANDOM().
RoundingPolicy
SQLiteAggregateSupport
SQLiteDateTimeSupport
SQLiteMathSupport
SQLiteStringSupport
SequenceSupport
StatisticalAggregatePolicy
SubqueryType: Maps a select marker to the SQL type produced by that subquery.

Functions§

abs: ABS - returns the absolute value of a number.
age: AGE - calculates the interval between two timestamps (PostgreSQL).
alias: Create an aliased expression.
and: Logical AND of two conditions.
array_agg: ARRAY_AGG - aggregates values into a SQL array (PostgreSQL).
avg: AVG(expr) - calculates average of numeric values.
avg_distinct: AVG(DISTINCT expr) - calculates average of distinct numeric values.
between: BETWEEN comparison.
bool_and: BOOL_AND - true if all non-null inputs are true (PostgreSQL).
bool_or: BOOL_OR - true if any non-null input is true (PostgreSQL).
case: Start building a searched CASE expression.
cast: Cast an expression to a different type.
ceil: CEIL / CEILING - rounds a number up to the nearest integer.
char_length: CHAR_LENGTH - returns the number of characters in a string.
clock_timestamp: CLOCK_TIMESTAMP - returns the actual wall-clock time (PostgreSQL).
coalesce: COALESCE - returns first non-null value.
coalesce_many: COALESCE with multiple values.
collate: COLLATE - apply a named collation to a text expression.
concat: Concatenate two string expressions using || operator.
concat_ws: CONCAT_WS - concatenates values with a separator, skipping NULLs.
count: COUNT aggregate.
count_distinct: COUNT(DISTINCT expr) - counts distinct non-null values.
cume_dist: CUME_DIST() — cumulative distribution: fraction of rows <= current row.
current_date: CURRENT_DATE - returns the current date.
current_time: CURRENT_TIME - returns the current time.
current_timestamp: CURRENT_TIMESTAMP - returns the current timestamp with time zone.
currval: CURRVAL - returns the most recently obtained value from a sequence (PostgreSQL).
date: DATE - extracts the date part from a temporal expression (SQLite).
date_bin: DATE_BIN - bins timestamps into intervals (PostgreSQL 14+).
date_trunc: DATE_TRUNC - truncates a timestamp to specified precision (PostgreSQL).
datetime: DATETIME - creates a datetime from a temporal expression (SQLite).
dense_rank: DENSE_RANK() — rank without gaps.
distinct: DISTINCT - marks an expression as DISTINCT.
eq: Equality comparison (=).
every: EVERY - true if all non-null inputs are true (PostgreSQL).
excluded: Reference a column’s value from the proposed insert row (EXCLUDED).
exists: EXISTS subquery check.
exp: EXP - returns e raised to the power of the argument.
extract: EXTRACT - extracts a component from a temporal expression (PostgreSQL/Standard SQL).
first_value: FIRST_VALUE(expr) — value of expr from the first row of the frame.
floor: FLOOR - rounds a number down to the nearest integer.
greatest: GREATEST - returns the largest of the given values (PostgreSQL).
group_concat: GROUP_CONCAT - concatenates values into a string (SQLite).
gt: Greater-than comparison (>).
gte: Greater-than-or-equal comparison (>=).
ifnull: IFNULL - SQLite/MySQL equivalent of COALESCE with two arguments.
in_array: IN array check.
in_subquery: IN subquery check.
initcap: INITCAP - converts the first letter of each word to uppercase (PostgreSQL).
instr: INSTR - finds the position of a substring.
is_distinct_from: IS DISTINCT FROM - NULL-safe inequality comparison.
is_false: IS FALSE - tests if a boolean expression is false.
is_not_distinct_from: IS NOT DISTINCT FROM - NULL-safe equality comparison.
is_not_null: IS NOT NULL check.
is_null: IS NULL check.
is_true: IS TRUE - tests if a boolean expression is true.
json_agg: JSON_AGG - aggregates values into a JSON array (PostgreSQL).
json_object_agg: JSON_OBJECT_AGG - aggregates key/value pairs into a JSON object (PostgreSQL).
jsonb_agg: JSONB_AGG - aggregates values into a JSONB array (PostgreSQL).
jsonb_object_agg: JSONB_OBJECT_AGG - aggregates key/value pairs into a JSONB object (PostgreSQL).
julianday: JULIANDAY - converts a temporal expression to Julian day number (SQLite).
lag: LAG(expr) — value of expr from the previous row.
lag_with_default: LAG(expr, offset, default) — value of expr from N rows back with a default.
last_value: LAST_VALUE(expr) — value of expr from the last row of the frame.
lead: LEAD(expr) — value of expr from the next row.
lead_with_default: LEAD(expr, offset, default) — value of expr from N rows ahead with a default.
least: LEAST - returns the smallest of the given values (PostgreSQL).
left: LEFT - returns the first n characters of a string (PostgreSQL).
length: LENGTH - returns the length of a string.
like: LIKE pattern matching.
ln: LN - returns the natural logarithm of a number.
localtime: LOCALTIME - returns the current time without time zone (PostgreSQL).
localtimestamp: LOCALTIMESTAMP - returns the current timestamp without time zone (PostgreSQL).
log: LOG - returns the logarithm of a number with a specified base.
log2: LOG2 - returns the base-2 logarithm of a number.
log10: LOG10 - returns the base-10 logarithm of a number.
lower: LOWER - converts string to lowercase.
lpad: LPAD - pads a string on the left to a specified length (PostgreSQL).
lt: Less-than comparison (<).
lte: Less-than-or-equal comparison (<=).
ltrim: LTRIM - removes leading whitespace.
make_date: MAKE_DATE - constructs a date from year, month, day (PostgreSQL).
make_timestamp: MAKE_TIMESTAMP - constructs a timestamp from components (PostgreSQL).
max: MAX(expr) - finds maximum value.
min: MIN(expr) - finds minimum value.
mod_: MOD - returns the remainder of division (using % operator).
ne: Inequality comparison (<>).
neq: Inequality comparison (<>).
nextval: NEXTVAL - advances a sequence and returns its new value (PostgreSQL).
not: Logical NOT.
not_between: NOT BETWEEN comparison.
not_exists: NOT EXISTS subquery check.
not_in_array: NOT IN array check.
not_in_subquery: NOT IN subquery check.
not_like: NOT LIKE pattern matching.
now: NOW - returns the current timestamp with time zone (PostgreSQL).
nth_value: NTH_VALUE(expr, n) — value of expr from the nth row of the frame.
ntile: NTILE(n) — divide rows into n roughly equal groups.
nullif: NULLIF - returns NULL if arguments are equal, else first argument.
octet_length: OCTET_LENGTH - returns the number of bytes in a string.
or: Logical OR of two conditions.
percent_rank: PERCENT_RANK() — relative rank of the current row: (rank - 1) / (total rows - 1).
pi: PI - returns the mathematical constant pi (PostgreSQL).
power: POWER - raises a number to a power.
random: RANDOM - returns a random value.
rank: RANK() — rank with gaps for ties.
raw: Create a raw SQL expression with a specified type.
raw_non_null: Create a raw SQL expression with explicit non-null nullability.
raw_nullable: Create a raw SQL expression with explicit nullable nullability.
regexp_match: REGEXP_MATCH - returns captured groups from the first POSIX regex match (PostgreSQL).
regexp_match_flags: REGEXP_MATCH with flags (PostgreSQL).
regexp_replace: REGEXP_REPLACE - replaces substrings matching a POSIX regex (PostgreSQL).
regexp_replace_flags: REGEXP_REPLACE with flags - replaces substrings matching a POSIX regex (PostgreSQL).
repeat: REPEAT - repeats a string n times (PostgreSQL).
replace: REPLACE - replaces occurrences of a substring.
reverse: REVERSE - reverses a string (PostgreSQL).
right: RIGHT - returns the last n characters of a string (PostgreSQL).
round: ROUND - rounds a number to the nearest integer (or specified precision).
round_to: ROUND with precision - rounds a number to specified decimal places.
row_number: ROW_NUMBER() — sequential row number within the partition.
rpad: RPAD - pads a string on the right to a specified length (PostgreSQL).
rtrim: RTRIM - removes trailing whitespace.
setval: SETVAL - sets a sequence’s current value (PostgreSQL).
sign: SIGN - returns the sign of a number (-1, 0, or 1).
split_part: SPLIT_PART - splits a string and returns the nth field (PostgreSQL).
sqrt: SQRT - returns the square root of a number.
starts_with: STARTS_WITH - tests if a string starts with a prefix (PostgreSQL).
stddev_pop: STDDEV_POP - population standard deviation.
stddev_samp: STDDEV_SAMP / STDDEV - sample standard deviation.
strftime: STRFTIME - formats a temporal expression as text (SQLite).
string_agg: STRING_AGG - concatenates text values using a delimiter (PostgreSQL).
string_concat: Concatenate two string expressions using || operator.
strpos: STRPOS - finds the position of a substring (PostgreSQL).
substr: SUBSTR - extracts a substring from a string.
sum: SUM(expr) - sums numeric values.
sum_distinct: SUM(DISTINCT expr) - sums distinct numeric values.
time: TIME - extracts the time part from a temporal expression (SQLite).
timediff: TIMEDIFF - computes the difference between two temporal values (SQLite 3.43+).
to_char: TO_CHAR - formats a temporal expression as text (PostgreSQL).
to_date: TO_DATE - parses a date from text using a format pattern (PostgreSQL).
to_number: TO_NUMBER - parses a number from text using a format pattern (PostgreSQL).
to_timestamp: TO_TIMESTAMP - converts a Unix timestamp to a timestamp (PostgreSQL).
total: TOTAL - sums numeric values, returning 0.0 for empty sets (SQLite).
translate: TRANSLATE - replaces each character in from with the corresponding character in to (PostgreSQL).
trim: TRIM - removes leading and trailing whitespace.
trunc: TRUNC - truncates a number towards zero.
typeof: Alias for typeof_ (uses Rust raw identifier syntax).
typeof_: Get the SQL type of an expression.
unixepoch: UNIXEPOCH - converts a temporal expression to Unix timestamp (SQLite 3.38+).
upper: UPPER - converts string to uppercase.
var_pop: VAR_POP - population variance.
var_samp: VAR_SAMP / VARIANCE - sample variance.
variance: VARIANCE - PostgreSQL alias for sample variance (VAR_SAMP).
window: Create an empty window specification.

Type Aliases§

AggExpr: An aggregate, non-null expression.
NullableAggExpr: An aggregate, nullable expression.
NullableExpr: A scalar, nullable expression.
ScalarExpr: A scalar, non-null expression.

Module expr

Module expr Copy item path

§Example

Structs§

Enums§

Traits§

Functions§

Type Aliases§

Module expr