diff --git a/.github/workflows/static.yml b/.github/workflows/static.yml
index 0b170765..b7778798 100644
--- a/.github/workflows/static.yml
+++ b/.github/workflows/static.yml
@@ -39,6 +39,7 @@ jobs:
           - '8.0'
           - '8.1'
           - '8.2'
+          - '8.3'
 
     steps:
       - name: Checkout.
@@ -70,4 +71,9 @@ jobs:
         run: composer update --no-interaction --no-progress --optimize-autoloader --ansi
 
       - name: Static analysis.
+        if: ${{ matrix.php != '8.0' }}
         run: vendor/bin/psalm --config=${{ inputs.psalm-config }} --shepherd --stats --output-format=github --php-version=${{ matrix.php }}
+
+      - name: Static analysis.
+        if: ${{ matrix.php == '8.0' }}
+        run: vendor/bin/psalm --config=psalm4.xml --shepherd --stats --output-format=github --php-version=${{ matrix.php }}
diff --git a/CHANGELOG.md b/CHANGELOG.md
index b78d56f3..3dc7d3b3 100644
--- a/CHANGELOG.md
+++ b/CHANGELOG.md
@@ -5,6 +5,7 @@
 - Enh #281: Remove unused code in `Command` class (@vjik)
 - Enh #282: Change property `Schema::$typeMap` to constant `Schema::TYPE_MAP` (@Tigrov)
 - Enh #283: Remove unnecessary check for array type in `Schema::loadTableIndexes()` (@Tigrov)
+- Enh #288: Minor refactoring of `DDLQueryBuilder` and `Schema` (@Tigrov)
 
 ## 1.1.0 November 12, 2023
 
diff --git a/composer.json b/composer.json
index c2223a5a..5e57c922 100644
--- a/composer.json
+++ b/composer.json
@@ -34,7 +34,7 @@
         "rector/rector": "^0.19",
         "roave/infection-static-analysis-plugin": "^1.16",
         "spatie/phpunit-watcher": "^1.23",
-        "vimeo/psalm": "^4.3|^5.6",
+        "vimeo/psalm": "^4.30|^5.20",
         "yiisoft/aliases": "^2.0",
         "yiisoft/cache-file": "^3.1",
         "yiisoft/json": "^1.0",
diff --git a/psalm.xml b/psalm.xml
index 10d319ae..906206a6 100644
--- a/psalm.xml
+++ b/psalm.xml
@@ -15,5 +15,6 @@
     </projectFiles>
     <issueHandlers>
         <MixedAssignment errorLevel="suppress"/>
+        <RiskyTruthyFalsyComparison errorLevel="suppress" />
     </issueHandlers>
 </psalm>
diff --git a/psalm4.xml b/psalm4.xml
new file mode 100644
index 00000000..10d319ae
--- /dev/null
+++ b/psalm4.xml
@@ -0,0 +1,19 @@
+<?xml version="1.0"?>
+<psalm
+    errorLevel="1"
+    findUnusedBaselineEntry="true"
+    findUnusedCode="false"
+    xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+    xmlns="https://getpsalm.org/schema/config"
+    xsi:schemaLocation="https://getpsalm.org/schema/config vendor/vimeo/psalm/config.xsd"
+>
+    <projectFiles>
+        <directory name="src"/>
+        <ignoreFiles>
+            <directory name="vendor"/>
+        </ignoreFiles>
+    </projectFiles>
+    <issueHandlers>
+        <MixedAssignment errorLevel="suppress"/>
+    </issueHandlers>
+</psalm>
diff --git a/src/DDLQueryBuilder.php b/src/DDLQueryBuilder.php
index 84a9c89b..15b8cd92 100644
--- a/src/DDLQueryBuilder.php
+++ b/src/DDLQueryBuilder.php
@@ -105,8 +105,8 @@ public function createIndex(
             [$schema, $table] = $tableParts;
         }
 
-        return 'CREATE ' . ($indexType ? ($indexType . ' ') : '') . 'INDEX '
-            . $this->quoter->quoteTableName(($schema ? $schema . '.' : '') . $name)
+        return 'CREATE ' . (!empty($indexType) ? $indexType . ' ' : '') . 'INDEX '
+            . $this->quoter->quoteTableName((!empty($schema) ? $schema . '.' : '') . $name)
             . ' ON '
             . $this->quoter->quoteTableName($table)
             . ' (' . $this->queryBuilder->buildColumns($columns) . ')';
diff --git a/src/Schema.php b/src/Schema.php
index 23d46723..3d2853c1 100644
--- a/src/Schema.php
+++ b/src/Schema.php
@@ -752,7 +752,7 @@ private function getJsonColumns(TableSchemaInterface $table): array
         $regexp = '/\bjson_valid\(\s*["`\[]?(.+?)["`\]]?\s*\)/i';
 
         foreach ($checks as $check) {
-            if (preg_match_all($regexp, $check->getExpression(), $matches, PREG_SET_ORDER)) {
+            if (preg_match_all($regexp, $check->getExpression(), $matches, PREG_SET_ORDER) > 0) {
                 foreach ($matches as $match) {
                     $result[] = $match[1];
                 }