diff --git a/finnow-api/source/account/data_impl_sqlite.d b/finnow-api/source/account/data_impl_sqlite.d
index e37b2b4..c68f5a9 100644
--- a/finnow-api/source/account/data_impl_sqlite.d
+++ b/finnow-api/source/account/data_impl_sqlite.d
@@ -53,7 +53,32 @@ SQL");
     }
 
     Account update(ulong id, in Account newData) {
-        return newData; // TODO:
+        return doTransaction(db, () {
+            Account oldAccount = this.findById(id).orElseThrow("Account doesn't exist.");
+            bool typeDiff = oldAccount.type != newData.type;
+            bool numberSuffixDiff = oldAccount.numberSuffix != newData.numberSuffix;
+            bool nameDiff = oldAccount.name != newData.name;
+            bool currencyDiff = oldAccount.currency != newData.currency;
+            bool descriptionDiff = oldAccount.description != newData.description;
+            util.sqlite.update(
+                db,
+                q"SQL
+                UPDATE account
+                SET type = ?,
+                    number_suffix = ?,
+                    name = ?,
+                    currency = ?,
+                    description = ?
+                WHERE id = ?
+SQL",
+                newData.type.id,
+                newData.numberSuffix,
+                newData.name,
+                newData.currency.code,
+                newData.description
+            );
+            return this.findById(id).orElseThrow("Account doesn't exist");
+        });
     }
 
     void deleteById(ulong id) {
@@ -76,14 +101,45 @@ SQL");
     }
 
     AccountCreditCardProperties getCreditCardProperties(ulong id) {
-        Statement stmt = db.prepare("SELECT * FROM account_credit_card_properties WHERE account_id = ?");
-        stmt.bind(1, id);
-        ResultRange result = stmt.execute();
-        return parseCreditCardProperties(result.front);
+        Account account = findById(id).orElseThrow("Account doesn't exist.");
+        if (account.type != AccountTypes.CREDIT_CARD) throw new Exception("Account is not credit card.");
+        auto optionalProps = findOne(
+            db,
+            "SELECT * FROM account_credit_card_properties WHERE account_id = ?",
+            &parseCreditCardProperties,
+            id
+        );
+        if (!optionalProps.isNull) return optionalProps.value;
+        // No properties exist, so set them and return the new data.
+        AccountCreditCardProperties props;
+        props.account_id = account.id;
+        props.creditLimit = -1;
+        util.sqlite.update(
+            db,
+            "INSERT INTO account_credit_card_properties (account_id, credit_limit) VALUES (?, ?)",
+            props.account_id,
+            props.creditLimit
+        );
+        return props;
     }
 
     void setCreditCardProperties(ulong id, in AccountCreditCardProperties props) {
-        // TODO:
+        bool hasProps = exists(db, "SELECT * FROM account_credit_card_properties WHERE account_id = ?", id);
+        if (hasProps) {
+            util.sqlite.update(
+                db,
+                "UPDATE account_credit_card_properties SET credit_limit = ? WHERE account_id = ?",
+                props.creditLimit,
+                id
+            );
+        } else {
+            util.sqlite.update(
+                db,
+                "INSERT INTO account_credit_card_properties (account_id, credit_limit) VALUES (?, ?)",
+                id,
+                props.creditLimit
+            );
+        }
     }
 
     History getHistory(ulong id) {
diff --git a/finnow-api/source/util/sqlite.d b/finnow-api/source/util/sqlite.d
index e866383..4e5b164 100644
--- a/finnow-api/source/util/sqlite.d
+++ b/finnow-api/source/util/sqlite.d
@@ -74,7 +74,8 @@ int update(Args...)(Database db, string query, Args args) {
  * Params:
  *   db = The database to use.
  *   dg = The delegate block of code to run in the transaction.
- * Returns: The return value of the delegate.
+ * Returns: The return value of the delegate, if the delegate does indeed
+ * return something.
  */
 T doTransaction(T)(Database db, T delegate() dg) {
     try {