diff --git a/.idea/misc.xml b/.idea/misc.xml
index 29af3ee..fcc1aa4 100644
--- a/.idea/misc.xml
+++ b/.idea/misc.xml
@@ -4,4 +4,7 @@
   <component name="ProjectRootManager" version="2" languageLevel="JDK_11" project-jdk-name="11" project-jdk-type="JavaSDK">
     <output url="file://$PROJECT_DIR$/out" />
   </component>
+  <component name="TaskProjectConfiguration">
+    <server type="GitHub" url="https://github.com" />
+  </component>
 </project>
\ No newline at end of file
diff --git a/.idea/modules.xml b/.idea/modules.xml
new file mode 100644
index 0000000..c2af880
--- /dev/null
+++ b/.idea/modules.xml
@@ -0,0 +1,8 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="ProjectModuleManager">
+    <modules>
+      <module fileurl="file://$PROJECT_DIR$/.idea/postgres-json.iml" filepath="$PROJECT_DIR$/.idea/postgres-json.iml" />
+    </modules>
+  </component>
+</project>
\ No newline at end of file
diff --git a/.idea/postgres-json.iml b/.idea/postgres-json.iml
new file mode 100644
index 0000000..d6ebd48
--- /dev/null
+++ b/.idea/postgres-json.iml
@@ -0,0 +1,9 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<module type="JAVA_MODULE" version="4">
+  <component name="NewModuleRootManager" inherit-compiler-output="true">
+    <exclude-output />
+    <content url="file://$MODULE_DIR$" />
+    <orderEntry type="inheritedJdk" />
+    <orderEntry type="sourceFolder" forTests="false" />
+  </component>
+</module>
\ No newline at end of file
diff --git a/.idea/sqldialects.xml b/.idea/sqldialects.xml
new file mode 100644
index 0000000..6df4889
--- /dev/null
+++ b/.idea/sqldialects.xml
@@ -0,0 +1,6 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project version="4">
+  <component name="SqlDialectMappings">
+    <file url="PROJECT" dialect="PostgreSQL" />
+  </component>
+</project>
\ No newline at end of file
diff --git a/src/main/kotlin/fr/postgresjson/connexion/Connection.kt b/src/main/kotlin/fr/postgresjson/connexion/Connection.kt
index deeaa30..307489d 100644
--- a/src/main/kotlin/fr/postgresjson/connexion/Connection.kt
+++ b/src/main/kotlin/fr/postgresjson/connexion/Connection.kt
@@ -10,13 +10,20 @@ import fr.postgresjson.entity.EntityI
 import fr.postgresjson.serializer.Serializer
 import java.util.concurrent.CompletableFuture
 
+
+interface Executable {
+    fun <T, R : EntityI<T?>?> select(sql: String, typeReference: TypeReference<R>, values: List<Any?> = emptyList()): R?
+    fun <T, R : List<EntityI<T?>?>> select(sql: String, typeReference: TypeReference<R>, values: List<Any?> = emptyList()): R?
+    fun exec(sql: String, values: List<Any?> = emptyList()): CompletableFuture<QueryResult>
+}
+
 class Connection(
     private val database: String,
     private val username: String,
     private val password: String,
     private val host: String = "localhost",
     private val port: Int = 5432
-) {
+): Executable {
     private lateinit var connection: ConnectionPool<PostgreSQLConnection>
     private val serializer = Serializer()
 
@@ -31,7 +38,7 @@ class Connection(
 
     fun <A> inTransaction(f: (Connection) -> CompletableFuture<A>) = connect().inTransaction(f)
 
-    fun <T, R : EntityI<T?>?> selectOne(sql: String, typeReference: TypeReference<R>, values: List<Any?> = emptyList()): R? {
+    override fun <T, R : EntityI<T?>?> select(sql: String, typeReference: TypeReference<R>, values: List<Any?>): R? {
         val future = connect().sendPreparedStatement(sql, compileArgs(values))
         val json = future.get().rows[0].getString(0)
         return if (json === null) {
@@ -41,9 +48,9 @@ class Connection(
         }
     }
 
-    inline fun <T, reified R : EntityI<T?>?> selectOne(sql: String, values: List<Any?> = emptyList()): R? = selectOne(sql, object: TypeReference<R>() {}, values)
+    inline fun <T, reified R : EntityI<T?>?> selectOne(sql: String, values: List<Any?> = emptyList()): R? = select(sql, object: TypeReference<R>() {}, values)
 
-    fun <T, R : List<EntityI<T?>?>> select(sql: String, typeReference: TypeReference<R>, values: List<Any?> = emptyList()): R {
+    override fun <T, R : List<EntityI<T?>?>> select(sql: String, typeReference: TypeReference<R>, values: List<Any?>): R {
         val future = connect().sendPreparedStatement(sql, compileArgs(values))
         val json = future.get().rows[0].getString(0)
         return if (json === null) {
@@ -55,7 +62,7 @@ class Connection(
 
     inline fun <T, reified R : List<EntityI<T?>?>> select(sql: String, values: List<Any?> = emptyList()): R = select(sql, object : TypeReference<R>() {}, values)
 
-    fun exec(sql: String, values: List<Any?> = emptyList()): CompletableFuture<QueryResult> {
+    override fun exec(sql: String, values: List<Any?>): CompletableFuture<QueryResult> {
         return connect().sendPreparedStatement(sql, compileArgs(values))
     }
 
diff --git a/src/main/kotlin/fr/postgresjson/connexion/Requester.kt b/src/main/kotlin/fr/postgresjson/connexion/Requester.kt
index 5f2d432..713f339 100644
--- a/src/main/kotlin/fr/postgresjson/connexion/Requester.kt
+++ b/src/main/kotlin/fr/postgresjson/connexion/Requester.kt
@@ -79,11 +79,11 @@ class Requester (
             return sql
         }
 
-        override fun <T, R : EntityI<T?>?> selectOne(typeReference: TypeReference<R>, values: List<Any?>): R? {
-            return connection.selectOne(this.toString(), typeReference, values)
+        override fun <T, R : EntityI<T?>?> select(typeReference: TypeReference<R>, values: List<Any?>): R? {
+            return connection.select(this.toString(), typeReference, values)
         }
 
-        inline fun <T, reified R : EntityI<T?>?> selectOne(values: List<Any?> = emptyList()): R? = selectOne(object: TypeReference<R>() {}, values)
+        inline fun <T, reified R : EntityI<T?>?> selectOne(values: List<Any?> = emptyList()): R? = select(object: TypeReference<R>() {}, values)
 
         override fun <T, R : List<EntityI<T?>?>> select(typeReference: TypeReference<R>, values: List<Any?>): R? {
             return connection.select(this.toString(), typeReference, values)
@@ -101,14 +101,14 @@ class Requester (
             return definition.name
         }
 
-        override fun <T, R : EntityI<T?>?> selectOne(typeReference: TypeReference<R>, values: List<Any?>): R? {
+        override fun <T, R : EntityI<T?>?> select(typeReference: TypeReference<R>, values: List<Any?>): R? {
             val args = compileArgs(values)
             val sql = "SELECT * FROM ${definition.name} ($args)"
 
-            return connection.selectOne(sql, typeReference, values)
+            return connection.select(sql, typeReference, values)
         }
 
-        inline fun <T, reified R: EntityI<T?>?> selectOne(values: List<String?> = emptyList()): R? = selectOne(object: TypeReference<R>() {}, values)
+        inline fun <T, reified R: EntityI<T?>?> selectOne(values: List<Any?> = emptyList()): R? = select(object: TypeReference<R>() {}, values)
 
         override fun <T, R : List<EntityI<T?>?>> select(typeReference: TypeReference<R>, values: List<Any?>): R? {
             val args = compileArgs(values)
@@ -143,7 +143,7 @@ class Requester (
         val connection : Connection
         override fun toString(): String
 
-        fun <T, R : EntityI<T?>?> selectOne(typeReference: TypeReference<R>, values: List<Any?> = emptyList()): R?
+        fun <T, R : EntityI<T?>?> select(typeReference: TypeReference<R>, values: List<Any?> = emptyList()): R?
 
         fun <T, R : List<EntityI<T?>?>> select(typeReference: TypeReference<R>, values: List<Any?> = emptyList()): R?
 
diff --git a/src/main/kotlin/fr/postgresjson/migration/Migrations.kt b/src/main/kotlin/fr/postgresjson/migration/Migrations.kt
index d517415..69400f3 100644
--- a/src/main/kotlin/fr/postgresjson/migration/Migrations.kt
+++ b/src/main/kotlin/fr/postgresjson/migration/Migrations.kt
@@ -15,9 +15,7 @@ class MigrationEntity(
     val up: String,
     val down: String,
     val version: Int
-): Entity<String?>(filename) {
-
-}
+): Entity<String?>(filename)
 
 interface Migration {
     var executedAt: Date?
@@ -177,16 +175,16 @@ class Migrations(directory: File, private val connection: Connection) {
 
     fun test(): Map<Pair<String, Direction>, Migration.Status> {
         var list: MutableMap<Pair<String, Direction>, Migration.Status> = mutableMapOf()
-        connection.inTransaction {
+        connection.connect().let {
+            it.sendQuery("BEGIN").join()
             up().map {
                 list.set(Pair(it.key, Direction.UP), it.value)
             }
             down().map {
                 list.set(Pair(it.key, Direction.DOWN), it.value)
             }
-
-            it.sendQuery("ROLLBACK");
-        }.join()
+            it.sendQuery("ROLLBACK").join()
+        }
 
         return list.toMap()
     }
diff --git a/src/main/kotlin/fr/postgresjson/migration/Query.kt b/src/main/kotlin/fr/postgresjson/migration/Query.kt
index 3924014..38736aa 100644
--- a/src/main/kotlin/fr/postgresjson/migration/Query.kt
+++ b/src/main/kotlin/fr/postgresjson/migration/Query.kt
@@ -12,14 +12,14 @@ class Query(
     override var executedAt: Date? = null
 ): Migration, Entity<String?>(name) {
     override fun up(): Migration.Status {
-        connection.exec(up)
+        connection.exec(up).join()
         // TODO insert to migration Table
 
         return Migration.Status.OK
     }
 
     override fun down(): Migration.Status {
-        connection.exec(down)
+        connection.exec(down).join()
         // TODO insert to migration Table
 
         return Migration.Status.OK
@@ -29,7 +29,7 @@ class Query(
         connection.inTransaction {
             up()
             down()
-            it.sendQuery("ROLLBACK");
+            it.sendQuery("ROLLBACK")
         }.join()
 
         return Migration.Status.OK // TODO