better error handling

Package.swift

@@ -8,7 +8,7 @@ let package = Package(
     platforms: [
         .iOS(.v13),
         .watchOS(.v6),
-        .tvOS(.v13)
+        .tvOS(.v13),
     ],
     products: [
         .executable(

README.md

@@ -15,7 +15,7 @@ The [Swift Package Manager](https://www.swift.org/documentation/package-manager/
 
 ```swift
 dependencies: [
-    .package(url: "https://github.com/jkrukowski/SQLiteVec", from: "0.0.4")
+    .package(url: "https://github.com/jkrukowski/SQLiteVec", from: "0.0.5")
 ]
 ```
 
@@ -51,20 +51,20 @@ try await db.execute("CREATE VIRTUAL TABLE vec_items USING vec0(embedding float[
 for row in data {
     try await db.execute(
         """
-            INSERT INTO vec_items(rowid, embedding) 
+            INSERT INTO vec_items(rowid, embedding)
             VALUES (?, ?)
-        """, 
+        """,
         params: [row.index, row.vector]
     )
 }
 
 // query the embeddings
 let result = try await db.query(
     """
-        SELECT rowid, distance 
-        FROM vec_items 
-        WHERE embedding MATCH ? 
-        ORDER BY distance 
+        SELECT rowid, distance
+        FROM vec_items
+        WHERE embedding MATCH ?
+        ORDER BY distance
         LIMIT 3
     """,
     params: [query]

Sources/SQLiteVec/Database.swift

@@ -53,7 +53,8 @@ public actor Database {
     private func prepare(_ sql: String, params: [Any]) throws -> OpaquePointer {
         var stmt: OpaquePointer?
         try SQLiteVecError.check(
-            sqlite3_prepare_v2(_handle, sql, -1, &stmt, nil)
+            sqlite3_prepare_v2(_handle, sql, -1, &stmt, nil),
+            _handle
         )
         let paramCount = Int(sqlite3_bind_parameter_count(stmt))
         guard paramCount == params.count else {
@@ -78,7 +79,7 @@ public actor Database {
             default:
                 result = sqlite3_bind_null(stmt, Int32(index + 1))
             }
-            try SQLiteVecError.check(result)
+            try SQLiteVecError.check(result, _handle)
         }
         return stmt!
     }

Sources/SQLiteVec/Models.swift

@@ -3,20 +3,48 @@ import Foundation
 
 struct SQLiteVecError: Error {
     let code: Int32
+    let message: String?
 
-    init(code: Int32) {
+    init(code: Int32, message: String?) {
         self.code = code
+        self.message = message
+    }
+}
+
+extension SQLiteVecError: CustomStringConvertible {
+    var description: String {
+        if let message {
+            "Error \(code): \(message)"
+        } else {
+            "Error \(code)"
+        }
+    }
+}
+
+extension SQLiteVecError: CustomDebugStringConvertible {
+    var debugDescription: String {
+        description
     }
 }
 
 extension SQLiteVecError {
     static let successCodes: Set = [SQLITE_OK, SQLITE_ROW, SQLITE_DONE]
 
-    static func check(_ code: Int32) throws {
+    static func check(_ code: Int32, _ handle: OpaquePointer? = nil) throws {
         if successCodes.contains(code) {
             return
         }
-        throw SQLiteVecError(code: code)
+        let message: String? =
+            if let handle {
+                String(cString: sqlite3_errmsg(handle))
+            } else {
+                nil
+            }
+        throw SQLiteVecError(code: code, message: message)
+    }
+
+    static func message(_ handle: OpaquePointer) -> String {
+        String(cString: sqlite3_errmsg(handle))
     }
 }
 

Tests/SQLiteVecTests/DatabaseTests.swift

@@ -36,6 +36,33 @@ final class DatabaseTests: XCTestCase {
         XCTAssertEqual(result[0]["name"] as? String, "Jane")
     }
 
+    func testSubQuery() async throws {
+        let db = try Database(.inMemory)
+        try await db.execute("""
+            CREATE TABLE users (
+                id INTEGER PRIMARY KEY,
+                name TEXT NOT NULL UNIQUE
+            )
+            """
+        )
+        try await db.execute("INSERT INTO users(id, name) VALUES (?, ?)", params: [1, "John"])
+        try await db.execute("INSERT INTO users(id, name) VALUES (?, ?)", params: [2, "Jane"])
+        try await db.execute("INSERT INTO users(id, name) VALUES (?, ?)", params: [3, "Jim"])
+
+        let result = try await db.query(
+            """
+                SELECT * FROM (
+                    SELECT * FROM users
+                    WHERE name LIKE 'J%'
+                ) as sub WHERE sub.id = ?
+            """,
+            params: [2]
+        )
+        XCTAssertEqual(result.count, 1)
+        XCTAssertEqual(result[0]["id"] as? Int, 2)
+        XCTAssertEqual(result[0]["name"] as? String, "Jane")
+    }
+
     func testQuantizeBinary() async throws {
         let db = try Database(.inMemory)
         let result = try await db.query(
@@ -103,18 +130,18 @@ final class DatabaseTests: XCTestCase {
         for row in data {
             try await db.execute(
                 """
-                    INSERT INTO vec_items(rowid, embedding) 
+                    INSERT INTO vec_items(rowid, embedding)
                     VALUES (?, ?)
                 """,
                 params: [row.index, row.vector]
             )
         }
         let result = try await db.query(
             """
-                SELECT rowid, distance 
-                FROM vec_items 
-                WHERE embedding MATCH ? 
-                ORDER BY distance 
+                SELECT rowid, distance
+                FROM vec_items
+                WHERE embedding MATCH ?
+                ORDER BY distance
                 LIMIT 3
             """,
             params: [query]