Struct CaseStatement

pub struct CaseStatement { /* private fields */ }

Implementations

impl CaseStatement

pub fn new() -> CaseStatement

Creates a new case statement expression

Examples

use sea_query::{*, tests_cfg::*};

let query = Query::select()
    .expr_as(
        CaseStatement::new()
            .case(Expr::tbl(Glyph::Table, Glyph::Aspect).is_in(vec![2, 4]), Expr::val(true))
            .finally(Expr::val(false)),
         Alias::new("is_even")
    )
    .from(Glyph::Table)
    .to_owned();

assert_eq!(
    query.to_string(PostgresQueryBuilder),
    r#"SELECT (CASE WHEN ("glyph"."aspect" IN (2, 4)) THEN TRUE ELSE FALSE END) AS "is_even" FROM "glyph""#
);    

pub fn case<C, T>(self, cond: C, then: T) -> CaseStatement

where C: IntoCondition, T: Into<Expr>,

Adds new CASE WHEN to existing case statement.

Examples

use sea_query::{*, tests_cfg::*};

let query = Query::select()
    .expr_as(
            Expr::case(
                Expr::tbl(Glyph::Table, Glyph::Aspect).gt(0),
                Expr::val("positive")
             )
            .case(
                Expr::tbl(Glyph::Table, Glyph::Aspect).lt(0),
                Expr::val("negative")
             )
            .finally(Expr::val("zero")),
         Alias::new("polarity")
    )
    .from(Glyph::Table)
    .to_owned();

assert_eq!(
    query.to_string(PostgresQueryBuilder),
    r#"SELECT (CASE WHEN ("glyph"."aspect" > 0) THEN 'positive' WHEN ("glyph"."aspect" < 0) THEN 'negative' ELSE 'zero' END) AS "polarity" FROM "glyph""#
);    

pub fn finally<E>(self, else: E) -> CaseStatement

where E: Into<Expr>,

Ends the case statement with the final ELSE result.

Examples

use sea_query::{*, tests_cfg::*};

let query = Query::select()
    .expr_as(
        Expr::case(
            Cond::any()
                .add(Expr::tbl(Character::Table, Character::FontSize).gt(48))
                .add(Expr::tbl(Character::Table, Character::SizeW).gt(500)),
            Expr::val("large")
        )
        .case(
            Cond::any()
                .add(Expr::tbl(Character::Table, Character::FontSize).between(24,48).into_condition())
                .add(Expr::tbl(Character::Table, Character::SizeW).between(300,500).into_condition()),
            Expr::val("medium")
        )
        .finally(Expr::val("small")),
        Alias::new("char_size"))
    .from(Character::Table)
    .to_owned();

assert_eq!(
    query.to_string(PostgresQueryBuilder),
    [
        r#"SELECT"#,
        r#"(CASE WHEN ("character"."font_size" > 48 OR "character"."size_w" > 500) THEN 'large'"#,
        r#"WHEN (("character"."font_size" BETWEEN 24 AND 48) OR ("character"."size_w" BETWEEN 300 AND 500)) THEN 'medium'"#,
        r#"ELSE 'small' END) AS "char_size""#,
        r#"FROM "character""#
    ]
    .join(" ")
);    

Trait Implementations

impl Clone for CaseStatement

fn clone(&self) -> CaseStatement

Returns a duplicate of the value.

const fn clone_from(&mut self, source: &Self)

Performs copy-assignment from source.

impl Debug for CaseStatement

fn fmt(&self, f: &mut Formatter<'_>) -> Result<(), Error>

Formats the value using the given formatter.

impl Default for CaseStatement

fn default() -> CaseStatement

Returns the “default value” for a type.

impl Into<SimpleExpr> for CaseStatement

fn into(self) -> SimpleExpr

Converts this type into the (usually inferred) input type.