Join sql fragments

README.md

@@ -16,7 +16,7 @@ Includes
 <dependency>
     <groupId>dev.mccue</groupId>
     <artifactId>jdbc</artifactId>
-    <version>2024.11.25</version>
+    <version>2024.11.27</version>
 </dependency>
 ```
 
@@ -25,7 +25,7 @@ Includes
 
 ```groovy
 dependencies {
-    implementation("dev.mccue:jdbc:2024.11.25")
+    implementation("dev.mccue:jdbc:2024.11.27")
 }
 ```
 

pom.xml

@@ -6,7 +6,7 @@
 
     <groupId>dev.mccue</groupId>
     <artifactId>jdbc</artifactId>
-    <version>2024.11.25</version>
+    <version>2024.11.27</version>
     <packaging>jar</packaging>
 
     <properties>

src/main/java/dev/mccue/jdbc/SQLFragment.java

@@ -4,6 +4,8 @@
 import java.sql.PreparedStatement;
 import java.sql.SQLException;
 import java.util.ArrayList;
+import java.util.Collection;
+import java.util.Collections;
 import java.util.List;
 
 /**
@@ -16,15 +18,15 @@ public final class SQLFragment {
 
     private SQLFragment(String sql, List<?> parameters) {
         this.sql = sql;
-        this.parameters = List.copyOf(parameters);
+        this.parameters = Collections.unmodifiableList(new ArrayList<>(parameters));
     }
 
     public static SQLFragment of(String sql, List<?> parameters) {
         return new SQLFragment(sql, parameters);
     }
 
     public static SQLFragment of(String sql) {
-        return new SQLFragment(sql, List.of());
+        return new SQLFragment(sql, Collections.unmodifiableList(new ArrayList<>()));
     }
 
     public String sql() {
@@ -58,6 +60,22 @@ public SQLFragment concat(SQLFragment other) {
         return SQLFragment.of(sql + other.sql, params);
     }
 
+    public static SQLFragment join(String separator, Collection<SQLFragment> fragments) {
+        var params = new ArrayList<>();
+        var fragmentStr = new StringBuilder();
+
+        var iter = fragments.iterator();
+        while (iter.hasNext()) {
+            var fragment = iter.next();
+            params.addAll(fragment.parameters);
+            fragmentStr.append(fragment.sql);
+            if (iter.hasNext()) {
+                fragmentStr.append(separator);
+            }
+        }
+        return SQLFragment.of(fragmentStr.toString(), params);
+    }
+
     public PreparedStatement prepareStatement(Connection connection) throws SQLException {
         var stmt = connection.prepareStatement(sql);
         int i = 1;

src/test/java/dev/mccue/jdbc/test/SQLFragmentTest.java

@@ -0,0 +1,23 @@
+package dev.mccue.jdbc.test;
+
+import dev.mccue.jdbc.SQLFragment;
+import org.junit.jupiter.api.Test;
+
+import java.util.Arrays;
+
+import static org.junit.jupiter.api.Assertions.assertEquals;
+
+public class SQLFragmentTest {
+    @Test
+    public void allowsNullParams() {
+        var fragment = SQLFragment.of("SELECT ?", Arrays.asList(1, null, "a", null));
+        assertEquals(fragment.parameters(), Arrays.asList(1, null, "a", null));
+    }
+
+    @Test
+    public void concatsInOrder() {
+        var fragment = SQLFragment.of("SELECT ?", Arrays.asList(1, null, "a", null))
+                .concat(SQLFragment.of("FROM ?", Arrays.asList(5, 6)));
+        assertEquals(fragment.parameters(), Arrays.asList(1, null, "a", null, 5, 6));
+    }
+}