diff --git a/migra-cli/src/commands/apply.rs b/migra-cli/src/commands/apply.rs
index b64f52c..f873db3 100644
--- a/migra-cli/src/commands/apply.rs
+++ b/migra-cli/src/commands/apply.rs
@@ -1,12 +1,14 @@
 use crate::config::Config;
 use crate::database::PostgresConnection;
+use crate::migration::{DatabaseMigrationManager, MigrationManager};
 use crate::opts::ApplyCommandOpt;
 use crate::path::PathBuilder;
 use crate::StdResult;
 use std::convert::TryFrom;
 
 pub(crate) fn apply_sql(config: Config, opts: ApplyCommandOpt) -> StdResult<()> {
-    let mut connection = PostgresConnection::try_from(&config)?;
+    let connection = PostgresConnection::try_from(&config)?;
+    let mut manager = MigrationManager::new(connection);
 
     let file_path = PathBuilder::from(config.directory_path())
         .append(opts.file_name)
@@ -15,7 +17,7 @@ pub(crate) fn apply_sql(config: Config, opts: ApplyCommandOpt) -> StdResult<()>
 
     let content = std::fs::read_to_string(file_path)?;
 
-    match connection.apply_sql(&content) {
+    match manager.apply_sql(&content) {
         Ok(_) => {
             println!("File was applied successfully");
         }
diff --git a/migra-cli/src/commands/downgrade.rs b/migra-cli/src/commands/downgrade.rs
index d50377e..a8267ad 100644
--- a/migra-cli/src/commands/downgrade.rs
+++ b/migra-cli/src/commands/downgrade.rs
@@ -1,13 +1,14 @@
 use crate::config::Config;
 use crate::database::PostgresConnection;
-use crate::migration::Downgrade;
+use crate::migration::{DatabaseMigrationManager, MigrationManager};
 use crate::StdResult;
 use std::convert::TryFrom;
 
 pub(crate) fn downgrade_applied_migrations(config: Config) -> StdResult<()> {
-    let mut connection = PostgresConnection::try_from(&config)?;
+    let connection = PostgresConnection::try_from(&config)?;
+    let mut manager = MigrationManager::new(connection);
 
-    let applied_migrations = connection.applied_migration_names()?;
+    let applied_migrations = manager.applied_migration_names()?;
     let migrations = config.migrations()?;
 
     if let Some(first_applied_migration) = applied_migrations.first() {
@@ -16,7 +17,7 @@ pub(crate) fn downgrade_applied_migrations(config: Config) -> StdResult<()> {
             .find(|m| m.name() == first_applied_migration)
         {
             println!("downgrade {}...", migration.name());
-            migration.downgrade(&mut connection)?;
+            manager.downgrade(&migration)?;
         }
     }
 
diff --git a/migra-cli/src/commands/list.rs b/migra-cli/src/commands/list.rs
index ae3fdcf..d0fa8ec 100644
--- a/migra-cli/src/commands/list.rs
+++ b/migra-cli/src/commands/list.rs
@@ -1,26 +1,23 @@
 use crate::config::Config;
-use crate::database::PostgresConnection;
+use crate::database::{DatabaseConnection, PostgresConnection};
 use crate::error::{ErrorKind, StdResult};
+use crate::migration::{
+    filter_pending_migrations, DatabaseMigrationManager, Migration, MigrationManager,
+};
 
 const EM_DASH: char = '—';
 
 pub(crate) fn print_migration_lists(config: Config) -> StdResult<()> {
-    let applied_migrations = match config.database_connection_string() {
+    let applied_migration_names = match config.database_connection_string() {
         Ok(ref database_connection_string) => {
-            let mut connection = PostgresConnection::open(database_connection_string)?;
-            let applied_migrations = connection.applied_migration_names()?;
+            let connection = PostgresConnection::open(database_connection_string)?;
+            let mut manager = MigrationManager::new(connection);
 
-            println!("Applied migrations:");
-            if applied_migrations.is_empty() {
-                println!("{}", EM_DASH);
-            } else {
-                applied_migrations
-                    .iter()
-                    .rev()
-                    .for_each(|name| println!("{}", name));
-            }
+            let applied_migration_names = manager.applied_migration_names()?;
 
-            applied_migrations
+            show_applied_migrations(&applied_migration_names);
+
+            applied_migration_names
         }
         Err(e) if *e.kind() == ErrorKind::MissedEnvVar(String::new()) => {
             println!("{}", e.kind());
@@ -33,11 +30,26 @@ pub(crate) fn print_migration_lists(config: Config) -> StdResult<()> {
 
     println!();
 
-    let pending_migrations = config
-        .migrations()?
-        .into_iter()
-        .filter(|m| !applied_migrations.contains(m.name()))
-        .collect::<Vec<_>>();
+    let pending_migrations =
+        filter_pending_migrations(config.migrations()?, &applied_migration_names);
+    show_pending_migrations(&pending_migrations);
+
+    Ok(())
+}
+
+fn show_applied_migrations(applied_migration_names: &[String]) {
+    println!("Applied migrations:");
+    if applied_migration_names.is_empty() {
+        println!("{}", EM_DASH);
+    } else {
+        applied_migration_names
+            .iter()
+            .rev()
+            .for_each(|name| println!("{}", name));
+    }
+}
+
+fn show_pending_migrations(pending_migrations: &[Migration]) {
     println!("Pending migrations:");
     if pending_migrations.is_empty() {
         println!("{}", EM_DASH);
@@ -46,6 +58,4 @@ pub(crate) fn print_migration_lists(config: Config) -> StdResult<()> {
             println!("{}", m.name());
         });
     }
-
-    Ok(())
 }
diff --git a/migra-cli/src/commands/upgrade.rs b/migra-cli/src/commands/upgrade.rs
index 17fe2d8..16c6ff5 100644
--- a/migra-cli/src/commands/upgrade.rs
+++ b/migra-cli/src/commands/upgrade.rs
@@ -1,24 +1,21 @@
-use crate::database::PostgresConnection;
-use crate::migration::{Migration, Upgrade};
+use crate::database::{DatabaseConnection, PostgresConnection};
+use crate::migration::Migration;
+use crate::migration::{filter_pending_migrations, DatabaseMigrationManager, MigrationManager};
 use crate::Config;
 use crate::StdResult;
 use std::convert::TryFrom;
 
 pub(crate) fn upgrade_pending_migrations(config: Config) -> StdResult<()> {
-    let mut connection = PostgresConnection::try_from(&config)?;
+    let mut manager = MigrationManager::new(PostgresConnection::try_from(&config)?);
 
-    let applied_migration_names = connection.applied_migration_names()?;
+    let applied_migration_names = manager.applied_migration_names()?;
     let migrations = config.migrations()?;
 
     if is_up_to_date_migrations(&migrations, &applied_migration_names) {
         println!("Up to date");
     } else {
         let pending_migrations = filter_pending_migrations(migrations, &applied_migration_names);
-
-        for migration in pending_migrations.iter() {
-            println!("upgrade {}...", migration.name());
-            migration.upgrade(&mut connection)?;
-        }
+        upgrade_all_pending_migrations(manager, &pending_migrations)?;
     }
 
     Ok(())
@@ -28,12 +25,18 @@ fn is_up_to_date_migrations(migrations: &[Migration], applied_migration_names: &
     migrations.is_empty() || migrations.last().map(|m| m.name()) == applied_migration_names.first()
 }
 
-fn filter_pending_migrations(
-    migrations: Vec<Migration>,
-    applied_migration_names: &[String],
-) -> Vec<Migration> {
-    migrations
-        .into_iter()
-        .filter(|m| !applied_migration_names.contains(m.name()))
-        .collect()
+fn upgrade_all_pending_migrations<Conn, ManagerT>(
+    mut manager: ManagerT,
+    pending_migrations: &[Migration],
+) -> StdResult<()>
+where
+    Conn: DatabaseConnection,
+    ManagerT: Sized + DatabaseMigrationManager<Conn>,
+{
+    for migration in pending_migrations.iter() {
+        println!("upgrade {}...", migration.name());
+        manager.upgrade(migration)?;
+    }
+
+    Ok(())
 }
diff --git a/migra-cli/src/database.rs b/migra-cli/src/database.rs
index e66332a..e508aeb 100644
--- a/migra-cli/src/database.rs
+++ b/migra-cli/src/database.rs
@@ -1,8 +1,41 @@
 use crate::config::Config;
 use crate::StdResult;
-use postgres::{Client, Error, NoTls};
+use postgres::{Client, NoTls};
 use std::convert::TryFrom;
 
+pub trait ToSql {
+    fn to_sql(&self) -> String;
+}
+
+impl ToSql for &str {
+    fn to_sql(&self) -> String {
+        format!(r#""{}""#, self)
+    }
+}
+
+pub trait TryFromSql<QueryResultRow>: Sized {
+    fn try_from_sql(row: QueryResultRow) -> StdResult<Self>;
+}
+
+pub trait DatabaseConnection: Sized {
+    type QueryResultRow;
+    type QueryResult;
+
+    fn open(connection_string: &str) -> StdResult<Self>;
+
+    fn batch_execute(&mut self, query: &str) -> StdResult<()>;
+
+    fn execute<'b>(&mut self, query: &str, params: &'b [&'b dyn ToSql]) -> StdResult<u64>;
+
+    fn query<'b, OutputItem>(
+        &mut self,
+        query: &str,
+        params: &'b [&'b dyn ToSql],
+    ) -> StdResult<Vec<OutputItem>>
+    where
+        OutputItem: ?Sized + TryFromSql<Self::QueryResultRow>;
+}
+
 pub struct PostgresConnection {
     client: Client,
 }
@@ -15,54 +48,54 @@ impl TryFrom<&Config> for PostgresConnection {
     }
 }
 
-impl PostgresConnection {
-    pub fn open(connection_string: &str) -> StdResult<PostgresConnection> {
+impl DatabaseConnection for PostgresConnection {
+    type QueryResultRow = postgres::Row;
+    type QueryResult = Vec<Self::QueryResultRow>;
+
+    fn open(connection_string: &str) -> StdResult<Self> {
         let client = Client::connect(connection_string, NoTls)?;
         Ok(PostgresConnection { client })
     }
-}
 
-pub fn is_migrations_table_not_found(e: &Error) -> bool {
-    e.to_string()
-        .contains(r#"relation "migrations" does not exist"#)
-}
-
-impl PostgresConnection {
-    pub fn apply_sql(&mut self, sql_content: &str) -> Result<(), Error> {
-        self.client.batch_execute(sql_content)
+    fn batch_execute(&mut self, query: &str) -> StdResult<()> {
+        self.client.batch_execute(query)?;
+        Ok(())
     }
 
-    pub fn applied_migration_names(&mut self) -> Result<Vec<String>, Error> {
-        let res = self
-            .client
-            .query("SELECT name FROM migrations ORDER BY id DESC", &[])
-            .or_else(|e| {
-                if is_migrations_table_not_found(&e) {
-                    Ok(Vec::new())
-                } else {
-                    Err(e)
-                }
-            })?;
+    fn execute<'b>(&mut self, query: &str, params: &'b [&'b dyn ToSql]) -> StdResult<u64> {
+        let stmt = params
+            .iter()
+            .enumerate()
+            .fold(query.to_string(), |acc, (i, p)| {
+                str::replace(&acc, &format!("${}", i), &p.to_sql())
+            });
 
-        Ok(res.into_iter().map(|row| row.get(0)).collect())
+        let res = self.client.execute(stmt.as_str(), &[])?;
+        Ok(res)
     }
 
-    pub fn create_migrations_table(&mut self) -> Result<(), Error> {
-        self.apply_sql(
-            r#"CREATE TABLE IF NOT EXISTS migrations (
-                id      serial      PRIMARY KEY,
-                name    text        NOT NULL UNIQUE
-            )"#,
-        )
-    }
+    fn query<'b, OutputItem>(
+        &mut self,
+        query: &str,
+        params: &'b [&'b dyn ToSql],
+    ) -> StdResult<Vec<OutputItem>>
+    where
+        OutputItem: ?Sized + TryFromSql<Self::QueryResultRow>,
+    {
+        let stmt = params
+            .iter()
+            .enumerate()
+            .fold(query.to_string(), |acc, (i, p)| {
+                str::replace(&acc, &format!("${}", i), &p.to_sql())
+            });
 
-    pub fn insert_migration_info(&mut self, name: &str) -> Result<u64, Error> {
-        self.client
-            .execute("INSERT INTO migrations (name) VALUES ($1)", &[&name])
-    }
+        let res: Self::QueryResult = self.client.query(stmt.as_str(), &[])?;
 
-    pub fn delete_migration_info(&mut self, name: &str) -> Result<u64, Error> {
-        self.client
-            .execute("DELETE FROM migrations WHERE name = $1", &[&name])
+        let res = res
+            .into_iter()
+            .map(OutputItem::try_from_sql)
+            .collect::<Result<Vec<OutputItem>, _>>()?;
+
+        Ok(res)
     }
 }
diff --git a/migra-cli/src/migration.rs b/migra-cli/src/migration.rs
index ff53640..a509826 100644
--- a/migra-cli/src/migration.rs
+++ b/migra-cli/src/migration.rs
@@ -1,17 +1,10 @@
-use crate::database::PostgresConnection;
+use crate::database::TryFromSql;
+use crate::database::{DatabaseConnection, PostgresConnection};
 use crate::path::PathBuilder;
 use crate::StdResult;
 use std::fs;
 use std::path::PathBuf;
 
-pub trait Upgrade {
-    fn upgrade(&self, connection: &mut PostgresConnection) -> StdResult<()>;
-}
-
-pub trait Downgrade {
-    fn downgrade(&self, connection: &mut PostgresConnection) -> StdResult<()>;
-}
-
 #[derive(Debug)]
 pub struct Migration {
     upgrade_sql: PathBuf,
@@ -46,27 +39,122 @@ impl Migration {
     pub fn name(&self) -> &String {
         &self.name
     }
-}
 
-impl Upgrade for Migration {
-    fn upgrade(&self, connection: &mut PostgresConnection) -> StdResult<()> {
+    fn upgrade_sql_content(&self) -> StdResult<String> {
         let content = fs::read_to_string(&self.upgrade_sql)?;
-
-        connection.create_migrations_table()?;
-        connection.apply_sql(&content)?;
-        connection.insert_migration_info(self.name())?;
-
-        Ok(())
+        Ok(content)
     }
-}
 
-impl Downgrade for Migration {
-    fn downgrade(&self, connection: &mut PostgresConnection) -> StdResult<()> {
+    fn downgrade_sql_content(&self) -> StdResult<String> {
         let content = fs::read_to_string(&self.downgrade_sql)?;
+        Ok(content)
+    }
+}
 
-        connection.apply_sql(&content)?;
-        connection.delete_migration_info(self.name())?;
+pub struct MigrationManager<Conn: DatabaseConnection> {
+    conn: Conn,
+}
+
+impl<Conn: DatabaseConnection> MigrationManager<Conn> {
+    pub fn new(conn: Conn) -> Self {
+        MigrationManager { conn }
+    }
+}
+
+pub fn is_migrations_table_not_found<D: std::fmt::Display>(error: D) -> bool {
+    error
+        .to_string()
+        .contains(r#"relation "migrations" does not exist"#)
+}
+
+impl TryFromSql<postgres::Row> for String {
+    fn try_from_sql(row: postgres::Row) -> StdResult<Self> {
+        let res: String = row.get(0);
+        Ok(res)
+    }
+}
+
+pub trait DatabaseMigrationManager<Conn: DatabaseConnection> {
+    const CREATE_MIGRATIONS_STMT: &'static str = r#"
+        CREATE TABLE IF NOT EXISTS migrations (
+            id      serial      PRIMARY KEY,
+            name    text        NOT NULL UNIQUE
+        )
+    "#;
+
+    const INSERT_MIGRATION_STMT: &'static str = "INSERT INTO migrations (name) VALUES ($1)";
+
+    const DELETE_MIGRATION_STMT: &'static str = "DELETE FROM migrations WHERE name = $1";
+
+    fn apply_sql(&mut self, sql_content: &str) -> StdResult<()>;
+
+    fn applied_migration_names(&mut self) -> StdResult<Vec<String>>;
+
+    fn create_migrations_table(&mut self) -> StdResult<()>;
+
+    fn insert_migration_info(&mut self, name: &str) -> StdResult<u64>;
+
+    fn delete_migration_info(&mut self, name: &str) -> StdResult<u64>;
+
+    fn upgrade(&mut self, migration: &Migration) -> StdResult<()> {
+        let content = migration.upgrade_sql_content()?;
+
+        self.create_migrations_table()?;
+        self.apply_sql(&content)?;
+        self.insert_migration_info(migration.name())?;
+
+        Ok(())
+    }
+
+    fn downgrade(&mut self, migration: &Migration) -> StdResult<()> {
+        let content = migration.downgrade_sql_content()?;
+
+        self.apply_sql(&content)?;
+        self.delete_migration_info(migration.name())?;
 
         Ok(())
     }
 }
+
+impl DatabaseMigrationManager<PostgresConnection> for MigrationManager<PostgresConnection> {
+    fn apply_sql(&mut self, sql_content: &str) -> StdResult<()> {
+        self.conn.batch_execute(sql_content)
+    }
+
+    fn applied_migration_names(&mut self) -> StdResult<Vec<String>> {
+        let res = self
+            .conn
+            .query("SELECT name FROM migrations ORDER BY id DESC", &[])
+            .or_else(|e| {
+                if is_migrations_table_not_found(&e) {
+                    Ok(Vec::new())
+                } else {
+                    Err(e)
+                }
+            })?;
+
+        Ok(res.into_iter().collect())
+    }
+
+    fn create_migrations_table(&mut self) -> StdResult<()> {
+        self.conn.batch_execute(Self::CREATE_MIGRATIONS_STMT)
+    }
+
+    fn insert_migration_info(&mut self, name: &str) -> StdResult<u64> {
+        self.conn.execute(Self::INSERT_MIGRATION_STMT, &[&name])
+    }
+
+    fn delete_migration_info(&mut self, name: &str) -> StdResult<u64> {
+        self.conn.execute(Self::DELETE_MIGRATION_STMT, &[&name])
+    }
+}
+
+pub fn filter_pending_migrations(
+    migrations: Vec<Migration>,
+    applied_migration_names: &[String],
+) -> Vec<Migration> {
+    migrations
+        .into_iter()
+        .filter(|m| !applied_migration_names.contains(m.name()))
+        .collect()
+}