Further improved decimal to floating point conversion in Microsoft SQL Server

Author: lovasoa

CHANGELOG.md

@@ -5,6 +5,10 @@ All notable changes to this project will be documented in this file.
 The format is based on [Keep a Changelog](https://keepachangelog.com/en/1.0.0/),
 and this project adheres to [Semantic Versioning](https://semver.org/spec/v2.0.0.html).
 
+## 0.6.25
+
+- Further improved decimal to floating point conversion in Microsoft SQL Server
+
 ## 0.6.24
 
 - Improved decimal to floating point conversion in Postgres and Microsoft SQL Server

Cargo.lock

@@ -20,7 +20,7 @@ members = [
 
 [package]
 name = "sqlx-oldapi"
-version = "0.6.24"
+version = "0.6.25"
 license = "MIT OR Apache-2.0"
 readme = "README.md"
 repository = "https://github.com/lovasoa/sqlx"
@@ -125,8 +125,8 @@ bstr = ["sqlx-core/bstr"]
 git2 = ["sqlx-core/git2"]
 
 [dependencies]
-sqlx-core = { package = "sqlx-core-oldapi",  version = "0.6.24", path = "sqlx-core", default-features = false }
-sqlx-macros = { package = "sqlx-macros-oldapi", version = "0.6.24", path = "sqlx-macros", default-features = false, optional = true }
+sqlx-core = { package = "sqlx-core-oldapi",  version = "0.6.25", path = "sqlx-core", default-features = false }
+sqlx-macros = { package = "sqlx-macros-oldapi", version = "0.6.25", path = "sqlx-macros", default-features = false, optional = true }
 
 [dev-dependencies]
 anyhow = "1.0.52"

Cargo.toml

@@ -8,7 +8,7 @@ edition = "2021"
 [dependencies]
 # Primary crates
 axum = { version = "0.5.13", features = ["macros"] }
-sqlx = { package = "sqlx-oldapi",  version = "0.6.24", path = "../../../", features = ["runtime-tokio-rustls", "postgres", "time", "uuid"] }
+sqlx = { package = "sqlx-oldapi",  version = "0.6.25", path = "../../../", features = ["runtime-tokio-rustls", "postgres", "time", "uuid"] }
 tokio = { version = "1.20.1", features = ["rt-multi-thread", "macros"] }
 
 # Important secondary crates

examples/postgres/axum-social-with-tests/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "sqlx-cli"
-version = "0.6.24"
+version = "0.6.25"
 description = "Command-line utility for SQLx, the Rust SQL toolkit."
 edition = "2021"
 readme = "README.md"

sqlx-cli/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "sqlx-core-oldapi"
-version = "0.6.24"
+version = "0.6.25"
 repository = "https://github.com/lovasoa/sqlx"
 description = "Core of SQLx, the rust SQL toolkit. Not intended to be used directly."
 license = "MIT OR Apache-2.0"
@@ -101,7 +101,7 @@ offline = ["serde", "either/serde"]
 paste = "1.0.6"
 ahash = "0.8.3"
 atoi = "2.0.0"
-sqlx-rt = { path = "../sqlx-rt", version = "0.6.24", package = "sqlx-rt-oldapi" }
+sqlx-rt = { path = "../sqlx-rt", version = "0.6.25", package = "sqlx-rt-oldapi" }
 base64 = { version = "0.22", default-features = false, optional = true, features = ["std"] }
 bigdecimal_ = { version = "0.4.1", optional = true, package = "bigdecimal" }
 rust_decimal = { version = "1.19.0", optional = true }

sqlx-core/Cargo.toml

@@ -85,11 +85,12 @@ fn decode_numeric(bytes: &[u8], _precision: u8, mut scale: u8) -> Result<f64, Bo
     let mut fixed_bytes = [0u8; 16];
     fixed_bytes[0..rest.len()].copy_from_slice(rest);
     let mut numerator = u128::from_le_bytes(fixed_bytes);
-    let mut decimal_part = 0.;
-    while scale > 0 {
-        decimal_part += (numerator % 10) as f64 / 10_f64.powf(scale as f64);
+    while numerator % 10 == 0 && scale > 0 {
         numerator /= 10;
         scale -= 1;
     }
-    Ok(sign * ((numerator as f64) + decimal_part))
+    let denominator = 10u128.pow(scale as u32);
+    let integer_part = (numerator / denominator) as f64;
+    let fractional_part = (numerator % denominator) as f64 / denominator as f64;
+    Ok(sign * (integer_part + fractional_part))
 }

sqlx-core/src/mssql/types/float.rs

@@ -1,6 +1,6 @@
 [package]
 name = "sqlx-macros-oldapi"
-version = "0.6.24"
+version = "0.6.25"
 repository = "https://github.com/lovasoa/sqlx"
 description = "Macros for SQLx, the rust SQL toolkit. Not intended to be used directly."
 license = "MIT OR Apache-2.0"
@@ -75,8 +75,8 @@ heck = { version = "0.5" }
 either = "1.6.1"
 once_cell = "1.9.0"
 proc-macro2 = { version = "1.0.36", default-features = false }
-sqlx-core = { package = "sqlx-core-oldapi",  version = "0.6.24", default-features = false, features = ["any"], path = "../sqlx-core" }
-sqlx-rt = { version = "0.6.24", default-features = false, path = "../sqlx-rt", package = "sqlx-rt-oldapi" }
+sqlx-core = { package = "sqlx-core-oldapi",  version = "0.6.25", default-features = false, features = ["any"], path = "../sqlx-core" }
+sqlx-rt = { version = "0.6.25", default-features = false, path = "../sqlx-rt", package = "sqlx-rt-oldapi" }
 serde = { version = "1.0.132", features = ["derive"], optional = true }
 serde_json = { version = "1.0.73", optional = true }
 sha2 = { version = "0.10.0", optional = true }

sqlx-macros/Cargo.toml

@@ -1,6 +1,6 @@
 [package]
 name = "sqlx-rt-oldapi"
-version = "0.6.24"
+version = "0.6.25"
 repository = "https://github.com/launchbadge/sqlx"
 license = "MIT OR Apache-2.0"
 description = "Runtime abstraction used by SQLx, the Rust SQL toolkit. Not intended to be used directly."

sqlx-rt/Cargo.toml

@@ -54,6 +54,9 @@ test_type!(f64(
 test_type!(numeric<f64>(Mssql,
     "CAST(12 AS NUMERIC)" == 12_f64,
     "CAST(0.7 AS NUMERIC(2,1))" == 0.7_f64,
+    "CAST(0.3 AS NUMERIC(2,1))" == 0.3_f64,
+    "CAST(0.47 AS DECIMAL(3,2))" == 0.47_f64,
+    "CAST(0.29 AS DECIMAL(3,2))" == 0.29_f64,
     "CAST(0.5678 AS NUMERIC(10,4))" == 0.5678_f64,
     "CAST(0.0003 AS NUMERIC(10,4))" == 0.0003_f64,
     "CAST(0.00003 AS NUMERIC(10,5))" == 0.00003_f64,
@@ -63,6 +66,16 @@ test_type!(numeric<f64>(Mssql,
     "CAST(123456789.0123456789 AS NUMERIC(38,10))" == 123_456_789.012_345_67_f64,
     "CAST(123456789.0123456789012 AS NUMERIC(38,13))" == 123_456_789.012_345_67_f64,
     "CAST(123456789.012345678901234 AS NUMERIC(38,15))" == 123_456_789.012_345_67_f64,
+
+    "CAST(1.0000000000000001 AS NUMERIC(18,16))" == 1.0000000000000001_f64,
+    "CAST(0.99999999999999 AS NUMERIC(18,14))" == 0.99999999999999_f64,
+    "CAST(2.00000000000001 AS NUMERIC(18,14))" == 2.00000000000001_f64,
+    "CAST(333.33333333333333 AS NUMERIC(18,14))" == 333.33333333333333_f64,
+    "CAST(0.14285714285714 AS NUMERIC(18,14))" == 0.14285714285714_f64,
+    "CAST(9999999.99999999 AS NUMERIC(16,8))" == 9999999.99999999_f64, // Close to the precision limit
+    "CAST(9007199254740992 AS NUMERIC(16,0))" == 9007199254740992_f64,    // 2^53, largest integer that can be exactly represented as a f64
+    "CAST(0.000123456 AS NUMERIC(38,38))" == 0.000123456_f64,
+    "CAST(1e-38 AS NUMERIC(38,38))" == 1e-38_f64,
 ));
 
 test_type!(str_nvarchar<String>(Mssql,