diff --git a/.env.example b/.env.example
index 0e1e19c..23105d9 100644
--- a/.env.example
+++ b/.env.example
@@ -1,8 +1,17 @@
 VITE_STRIPE_PK=
 VITE_SENTRY_ENABLED=
 VITE_SENTRY_DSN=
-# staging / production
+### local,staging
 VITE_SENTRY_ENV=staging
+### prod
+# VITE_SENTRY_ENV=production
+
+### db:local
+DATABASE_URL='postgres://user:password@localhost:5432/core'
+### db:staging
+# DATABASE_URL='postgres://user:password@localhost:5555/core'
+### db:prod
+# DATABASE_URL='postgres://user:password@localhost:6666/core'
 
 CYPRESS_CRED_EMAIL='owner@cypress.test'
 CYPRESS_CRED_PASSWORD='12345678'
@@ -10,13 +19,21 @@ CYPRESS_TEST_PRIVATE_TOKEN='12345678'
 
 ### local
 VITE_API_BASE_URL='http://localhost:1337/api'
-VITE_API_BASE_URL='http://localhost:3000'
+VITE_SITE_URL='http://localhost:3000'
 CYPRESS_API_BASE_URL='http://localhost:1337/api'
 
 # this variable will not switch
-DEBUG=1
+GRAPHQL_PLAYGROUND=1
 
 ### staging
 # VITE_API_BASE_URL='https://app.develop.staging.example.com/api'
-# VITE_BMM_SITE_URL='https://www.develop.staging.example.com'
+# VITE_SITE_URL='https://www.develop.staging.example.com'
 # CYPRESS_API_BASE_URL='https://app.develop.staging.example.com/api'
+
+### debug
+# DEBUG_VAR=1
+
+### debug:on,local
+# DEBUG=1
+### debug:off,staging
+# DEBUG=
diff --git a/.gitignore b/.gitignore
index 83a00ee..cb094d2 100644
--- a/.gitignore
+++ b/.gitignore
@@ -1,3 +1,4 @@
 /target
 
-.env
+.env*
+!.env.example
diff --git a/Cargo.toml b/Cargo.toml
index a714bd2..6e71447 100644
--- a/Cargo.toml
+++ b/Cargo.toml
@@ -12,3 +12,5 @@ categories = ["command-line-interface", "config", "development-tools"]
 
 [dependencies]
 clap = { version = "3.2.15", features = ["derive"] }
+
+[features]
diff --git a/README.md b/README.md
index fe351b3..298e36b 100644
--- a/README.md
+++ b/README.md
@@ -15,11 +15,26 @@ You can see the [full example].
 
 # Usage
 
+Basic usage
+
 ```sh
 cp .env.example .env
-vnetod local    # choose local state
-vnetod staging  # choose staging state
-vnetod -        # disable all states
+vnetod local        # enable local section
+vnetod staging      # enable staging section
+vnetod local debug  # enable local and debug sections
+vnetod              # disable all sections
+```
+
+You can also use variables from namespaces
+
+```sh
+vnetod db:staging debug:off
+```
+
+You can switch between states and overwrite from namespaces at the same time.
+
+```sh
+vnetod local db:staging debug:off
 ```
 
 # License
diff --git a/src/cli.rs b/src/cli.rs
index 46d599f..e236cf0 100644
--- a/src/cli.rs
+++ b/src/cli.rs
@@ -14,6 +14,8 @@
 //! along with vnetod.  If not, see <https://www.gnu.org/licenses/>.
 //!
 
+pub mod switch;
+
 use std::path::PathBuf;
 
 use clap::Parser;
@@ -40,5 +42,5 @@ pub struct Args {
     pub output: Option<PathBuf>,
 
     #[clap(value_parser)]
-    pub section_names: Vec<String>,
+    pub sections: Vec<String>,
 }
diff --git a/src/cli/switch.rs b/src/cli/switch.rs
new file mode 100644
index 0000000..a48ae7c
--- /dev/null
+++ b/src/cli/switch.rs
@@ -0,0 +1,32 @@
+use crate::{cli::Args, domain};
+use std::fs::File;
+
+#[derive(Debug)]
+pub enum Error {
+    OpenFile,
+    Switch(domain::switch::Error),
+}
+
+impl std::fmt::Display for Error {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Error::OpenFile => f.write_str("Cannot open file"),
+            Error::Switch(inner) => write!(f, "Cannot switch between states: {}", inner),
+        }
+    }
+}
+
+impl std::error::Error for Error {}
+
+pub fn execute(args: &Args) -> Result<(), Error> {
+    let content = std::fs::read_to_string(&args.file).map_err(|_| Error::OpenFile)?;
+    let writer =
+        File::create(args.output.as_ref().unwrap_or(&args.file)).map_err(|_| Error::OpenFile)?;
+
+    domain::switch::execute(domain::switch::Request {
+        content: &content,
+        writer,
+        sections: &args.sections,
+    })
+    .map_err(Error::Switch)
+}
diff --git a/src/domain.rs b/src/domain.rs
new file mode 100644
index 0000000..0898b8b
--- /dev/null
+++ b/src/domain.rs
@@ -0,0 +1,29 @@
+pub mod switch;
+
+#[derive(Debug, Clone, PartialEq, Eq)]
+struct Section {
+    namespace: Option<String>,
+    name: String,
+}
+
+impl Section {
+    fn new(name: &str) -> Self {
+        Self {
+            name: name.to_string(),
+            namespace: None,
+        }
+    }
+
+    fn with_namespace(namespace: &str, name: &str) -> Self {
+        Self {
+            name: name.to_string(),
+            namespace: Some(namespace.to_string()),
+        }
+    }
+
+    fn parse(s: &str) -> Self {
+        let s = s.trim();
+        s.split_once(':')
+            .map_or_else(|| Self::new(s), |(ns, name)| Self::with_namespace(ns, name))
+    }
+}
diff --git a/src/domain/switch.rs b/src/domain/switch.rs
new file mode 100644
index 0000000..25d4a98
--- /dev/null
+++ b/src/domain/switch.rs
@@ -0,0 +1,262 @@
+use std::io::{BufWriter, Write};
+
+use super::Section;
+
+#[derive(Debug)]
+pub enum Error {
+    WriteData,
+}
+
+impl std::fmt::Display for Error {
+    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {
+        match self {
+            Error::WriteData => f.write_str("Cannot write data"),
+        }
+    }
+}
+
+impl std::error::Error for Error {}
+
+pub struct Request<'args, W>
+where
+    W: Write,
+{
+    pub content: &'args str,
+    pub writer: W,
+    pub sections: &'args [String],
+}
+
+pub fn execute<W>(req: Request<W>) -> Result<(), Error>
+where
+    W: Write,
+{
+    let mut writer = BufWriter::new(req.writer);
+
+    let choose_sections = req
+        .sections
+        .iter()
+        .map(|s| Section::parse(s.as_str()))
+        .collect::<Vec<_>>();
+
+    let mut current_sections: Option<Vec<Section>> = None;
+
+    for line in req.content.split_inclusive('\n') {
+        let new_line = if is_section_end(line) {
+            current_sections = None;
+            line.to_string()
+        } else if let Some(section_info) = line.strip_prefix("### ") {
+            current_sections = section_info
+                .split_whitespace()
+                .next()
+                .map(|r| r.split(',').map(Section::parse).collect());
+            line.to_string()
+        } else if let Some(cur_sections) = current_sections.clone() {
+            let trimmed_line = line.trim_start_matches(['#', ' ']);
+            if should_enable_variable(&choose_sections, &cur_sections) {
+                String::from(trimmed_line)
+            } else if should_disable_variable(&choose_sections, &cur_sections) {
+                format!("# {}", trimmed_line)
+            } else {
+                line.to_string()
+            }
+        } else {
+            line.to_string()
+        };
+
+        writer
+            .write_all(new_line.as_bytes())
+            .map_err(|_| Error::WriteData)?;
+    }
+
+    writer.flush().map_err(|_| Error::WriteData)
+}
+
+fn is_section_end(line: &str) -> bool {
+    line.trim().is_empty()
+}
+
+fn should_enable_variable(choose_sections: &[Section], current_sections: &[Section]) -> bool {
+    let cross_sections = choose_sections
+        .iter()
+        .filter(|s| {
+            s.namespace.is_some()
+                && current_sections
+                    .iter()
+                    .any(|s2| s.namespace == s2.namespace)
+        })
+        .collect::<Vec<_>>();
+
+    if cross_sections.is_empty() {
+        choose_sections.iter().any(|s| {
+            if s.namespace.is_none() {
+                current_sections.iter().any(|s2| s.name == s2.name)
+            } else {
+                current_sections.contains(s)
+            }
+        })
+    } else {
+        cross_sections.iter().any(|s| current_sections.contains(s))
+    }
+}
+
+fn should_disable_variable(choose_sections: &[Section], current_sections: &[Section]) -> bool {
+    choose_sections.is_empty()
+        || choose_sections.iter().any(|s| s.namespace.is_none())
+        || choose_sections
+            .iter()
+            .filter(|s| s.namespace.is_some())
+            .any(|s| {
+                current_sections
+                    .iter()
+                    .any(|s2| s.namespace == s2.namespace && s.name != s2.name)
+            })
+}
+
+#[cfg(test)]
+mod tests {
+    use super::*;
+    use std::io::Cursor;
+
+    const BASE_ENV: &str = include_str!("../../test_data/base_env");
+
+    fn make_test(input: &str, expected_output: &str, sections: Vec<&str>) {
+        let mut output_data = vec![];
+        let writer = Cursor::new(&mut output_data);
+
+        match execute(Request {
+            content: input,
+            writer,
+            sections: &sections.into_iter().map(String::from).collect::<Vec<_>>(),
+        }) {
+            Ok(()) => {
+                let output = String::from_utf8(output_data).unwrap();
+                assert_eq!(
+                    output.lines().collect::<Vec<_>>(),
+                    expected_output.lines().collect::<Vec<_>>()
+                );
+            }
+            _ => unreachable!(),
+        }
+    }
+
+    #[test]
+    fn should_disable_all_sections() {
+        make_test(include_str!("../../test_data/all_env"), BASE_ENV, vec![]);
+    }
+
+    #[test]
+    fn should_enable_local_sections() {
+        make_test(
+            BASE_ENV,
+            include_str!("../../test_data/should_enable_local"),
+            vec!["local"],
+        );
+    }
+
+    #[test]
+    fn should_enable_staging_sections() {
+        make_test(
+            BASE_ENV,
+            include_str!("../../test_data/should_enable_staging"),
+            vec!["staging"],
+        );
+    }
+
+    #[test]
+    fn should_use_debug_in_staging_section() {
+        make_test(
+            BASE_ENV,
+            include_str!("../../test_data/should_use_debug_in_staging"),
+            vec!["staging", "debug:on"],
+        );
+    }
+
+    #[test]
+    fn should_use_staging_db_in_local_section() {
+        make_test(
+            BASE_ENV,
+            include_str!("../../test_data/should_use_staging_db_in_local"),
+            vec!["local", "db:staging"],
+        );
+    }
+
+    mod utils {
+        use super::*;
+
+        #[test]
+        fn should_not_enable_variables() {
+            assert!(!should_enable_variable(
+                &[Section::new("local")],
+                &[Section::new("staging")]
+            ));
+            assert!(!should_enable_variable(
+                &[Section::with_namespace("db", "local")],
+                &[Section::new("local")]
+            ));
+            assert!(!should_enable_variable(
+                &[Section::with_namespace("db", "local")],
+                &[Section::with_namespace("db", "staging")]
+            ));
+            assert!(!should_enable_variable(
+                &[
+                    Section::new("staging"),
+                    Section::with_namespace("debug", "on")
+                ],
+                &[
+                    Section::with_namespace("debug", "off"),
+                    Section::new("staging")
+                ]
+            ));
+        }
+
+        #[test]
+        fn should_enable_variables() {
+            assert!(should_enable_variable(
+                &[Section::new("local")],
+                &[Section::new("local")]
+            ));
+            assert!(should_enable_variable(
+                &[Section::new("local")],
+                &[Section::with_namespace("db", "local")]
+            ));
+            assert!(should_enable_variable(
+                &[Section::with_namespace("db", "local")],
+                &[Section::with_namespace("db", "local")]
+            ));
+            assert!(should_enable_variable(
+                &[
+                    Section::new("local"),
+                    Section::with_namespace("debug", "on")
+                ],
+                &[
+                    Section::with_namespace("debug", "on"),
+                    Section::new("staging")
+                ]
+            ));
+        }
+
+        #[test]
+        fn should_not_disable_variables() {
+            assert!(!should_disable_variable(
+                &[Section::with_namespace("debug", "on")],
+                &[Section::new("local")]
+            ));
+        }
+
+        #[test]
+        fn should_disable_variables() {
+            assert!(should_disable_variable(
+                &[Section::new("local")],
+                &[Section::with_namespace("debug", "off")]
+            ));
+            assert!(should_disable_variable(
+                &[],
+                &[Section::with_namespace("debug", "off")]
+            ));
+            assert!(should_disable_variable(
+                &[Section::with_namespace("debug", "on")],
+                &[Section::with_namespace("debug", "off")]
+            ));
+        }
+    }
+}
diff --git a/src/main.rs b/src/main.rs
index a9029f6..8c2fc7d 100644
--- a/src/main.rs
+++ b/src/main.rs
@@ -16,66 +16,14 @@
 #![deny(clippy::all, clippy::pedantic)]
 
 mod cli;
-
-use std::{
-    fs::File,
-    io::{BufWriter, Write},
-};
+mod domain;
 
 use clap::Parser;
 
-fn main() -> Result<(), Error> {
+fn main() -> Result<(), cli::switch::Error> {
     let cli = cli::Args::parse();
 
-    change_env_layout(&cli)?;
+    cli::switch::execute(&cli)?;
 
     Ok(())
 }
-
-fn change_env_layout(args: &cli::Args) -> Result<(), Error> {
-    let content = std::fs::read_to_string(&args.file).map_err(|_| Error::OpenFile)?;
-
-    let mut writer = File::create(args.output.as_ref().unwrap_or(&args.file))
-        .map_err(|_| Error::OpenFile)
-        .map(BufWriter::new)?;
-
-    let mut current_section_name: Option<Vec<String>> = None;
-
-    for line in content.split_inclusive('\n') {
-        let new_line = if is_section_end(line) {
-            current_section_name = None;
-            line.to_string()
-        } else if let Some(section_info) = line.strip_prefix("### ") {
-            current_section_name = section_info
-                .split_whitespace()
-                .next()
-                .map(|r| r.split(',').map(str::trim).map(String::from).collect());
-            line.to_string()
-        } else if let Some(cur_name) = current_section_name.clone() {
-            let trimmed_line = line.trim_start_matches(['#', ' ']);
-            if args.section_names.iter().any(|sn| cur_name.contains(sn)) {
-                String::from(trimmed_line)
-            } else {
-                format!("# {}", trimmed_line)
-            }
-        } else {
-            line.to_string()
-        };
-
-        writer
-            .write_all(new_line.as_bytes())
-            .map_err(|_| Error::WriteData)?;
-    }
-
-    writer.flush().map_err(|_| Error::WriteData)
-}
-
-fn is_section_end(line: &str) -> bool {
-    line.trim().is_empty()
-}
-
-#[derive(Debug)]
-enum Error {
-    OpenFile,
-    WriteData,
-}
diff --git a/test_data/all_env b/test_data/all_env
new file mode 100644
index 0000000..1583d32
--- /dev/null
+++ b/test_data/all_env
@@ -0,0 +1,36 @@
+VITE_STRIPE_PK=
+VITE_SENTRY_ENABLED=
+VITE_SENTRY_DSN=
+### local,staging
+VITE_SENTRY_ENV=staging
+### prod
+VITE_SENTRY_ENV=production
+
+### db:local
+DATABASE_URL='postgres://user:password@localhost:5432/core'
+### db:staging
+DATABASE_URL='postgres://user:password@localhost:5555/core'
+### db:prod
+DATABASE_URL='postgres://user:password@localhost:6666/core'
+
+CYPRESS_CRED_EMAIL='owner@cypress.test'
+CYPRESS_CRED_PASSWORD='12345678'
+CYPRESS_TEST_PRIVATE_TOKEN='12345678'
+
+### local
+VITE_API_BASE_URL='http://localhost:1337/api'
+VITE_SITE_URL='http://localhost:3000'
+CYPRESS_API_BASE_URL='http://localhost:1337/api'
+
+# this variable will not switch
+GRAPHQL_PLAYGROUND=1
+
+### staging
+VITE_API_BASE_URL='https://app.develop.staging.example.com/api'
+VITE_SITE_URL='https://www.develop.staging.example.com'
+CYPRESS_API_BASE_URL='https://app.develop.staging.example.com/api'
+
+### debug:on,local
+DEBUG=1
+### debug:off,staging
+DEBUG=
diff --git a/test_data/base_env b/test_data/base_env
new file mode 100644
index 0000000..6888eb6
--- /dev/null
+++ b/test_data/base_env
@@ -0,0 +1,36 @@
+VITE_STRIPE_PK=
+VITE_SENTRY_ENABLED=
+VITE_SENTRY_DSN=
+### local,staging
+# VITE_SENTRY_ENV=staging
+### prod
+# VITE_SENTRY_ENV=production
+
+### db:local
+# DATABASE_URL='postgres://user:password@localhost:5432/core'
+### db:staging
+# DATABASE_URL='postgres://user:password@localhost:5555/core'
+### db:prod
+# DATABASE_URL='postgres://user:password@localhost:6666/core'
+
+CYPRESS_CRED_EMAIL='owner@cypress.test'
+CYPRESS_CRED_PASSWORD='12345678'
+CYPRESS_TEST_PRIVATE_TOKEN='12345678'
+
+### local
+# VITE_API_BASE_URL='http://localhost:1337/api'
+# VITE_SITE_URL='http://localhost:3000'
+# CYPRESS_API_BASE_URL='http://localhost:1337/api'
+
+# this variable will not switch
+GRAPHQL_PLAYGROUND=1
+
+### staging
+# VITE_API_BASE_URL='https://app.develop.staging.example.com/api'
+# VITE_SITE_URL='https://www.develop.staging.example.com'
+# CYPRESS_API_BASE_URL='https://app.develop.staging.example.com/api'
+
+### debug:on,local
+# DEBUG=1
+### debug:off,staging
+# DEBUG=
diff --git a/test_data/should_enable_local b/test_data/should_enable_local
new file mode 100644
index 0000000..d6e4df7
--- /dev/null
+++ b/test_data/should_enable_local
@@ -0,0 +1,36 @@
+VITE_STRIPE_PK=
+VITE_SENTRY_ENABLED=
+VITE_SENTRY_DSN=
+### local,staging
+VITE_SENTRY_ENV=staging
+### prod
+# VITE_SENTRY_ENV=production
+
+### db:local
+DATABASE_URL='postgres://user:password@localhost:5432/core'
+### db:staging
+# DATABASE_URL='postgres://user:password@localhost:5555/core'
+### db:prod
+# DATABASE_URL='postgres://user:password@localhost:6666/core'
+
+CYPRESS_CRED_EMAIL='owner@cypress.test'
+CYPRESS_CRED_PASSWORD='12345678'
+CYPRESS_TEST_PRIVATE_TOKEN='12345678'
+
+### local
+VITE_API_BASE_URL='http://localhost:1337/api'
+VITE_SITE_URL='http://localhost:3000'
+CYPRESS_API_BASE_URL='http://localhost:1337/api'
+
+# this variable will not switch
+GRAPHQL_PLAYGROUND=1
+
+### staging
+# VITE_API_BASE_URL='https://app.develop.staging.example.com/api'
+# VITE_SITE_URL='https://www.develop.staging.example.com'
+# CYPRESS_API_BASE_URL='https://app.develop.staging.example.com/api'
+
+### debug:on,local
+DEBUG=1
+### debug:off,staging
+# DEBUG=
diff --git a/test_data/should_enable_staging b/test_data/should_enable_staging
new file mode 100644
index 0000000..a6b48fc
--- /dev/null
+++ b/test_data/should_enable_staging
@@ -0,0 +1,36 @@
+VITE_STRIPE_PK=
+VITE_SENTRY_ENABLED=
+VITE_SENTRY_DSN=
+### local,staging
+VITE_SENTRY_ENV=staging
+### prod
+# VITE_SENTRY_ENV=production
+
+### db:local
+# DATABASE_URL='postgres://user:password@localhost:5432/core'
+### db:staging
+DATABASE_URL='postgres://user:password@localhost:5555/core'
+### db:prod
+# DATABASE_URL='postgres://user:password@localhost:6666/core'
+
+CYPRESS_CRED_EMAIL='owner@cypress.test'
+CYPRESS_CRED_PASSWORD='12345678'
+CYPRESS_TEST_PRIVATE_TOKEN='12345678'
+
+### local
+# VITE_API_BASE_URL='http://localhost:1337/api'
+# VITE_SITE_URL='http://localhost:3000'
+# CYPRESS_API_BASE_URL='http://localhost:1337/api'
+
+# this variable will not switch
+GRAPHQL_PLAYGROUND=1
+
+### staging
+VITE_API_BASE_URL='https://app.develop.staging.example.com/api'
+VITE_SITE_URL='https://www.develop.staging.example.com'
+CYPRESS_API_BASE_URL='https://app.develop.staging.example.com/api'
+
+### debug:on,local
+# DEBUG=1
+### debug:off,staging
+DEBUG=
diff --git a/test_data/should_use_debug_in_staging b/test_data/should_use_debug_in_staging
new file mode 100644
index 0000000..6681dda
--- /dev/null
+++ b/test_data/should_use_debug_in_staging
@@ -0,0 +1,36 @@
+VITE_STRIPE_PK=
+VITE_SENTRY_ENABLED=
+VITE_SENTRY_DSN=
+### local,staging
+VITE_SENTRY_ENV=staging
+### prod
+# VITE_SENTRY_ENV=production
+
+### db:local
+# DATABASE_URL='postgres://user:password@localhost:5432/core'
+### db:staging
+DATABASE_URL='postgres://user:password@localhost:5555/core'
+### db:prod
+# DATABASE_URL='postgres://user:password@localhost:6666/core'
+
+CYPRESS_CRED_EMAIL='owner@cypress.test'
+CYPRESS_CRED_PASSWORD='12345678'
+CYPRESS_TEST_PRIVATE_TOKEN='12345678'
+
+### local
+# VITE_API_BASE_URL='http://localhost:1337/api'
+# VITE_SITE_URL='http://localhost:3000'
+# CYPRESS_API_BASE_URL='http://localhost:1337/api'
+
+# this variable will not switch
+GRAPHQL_PLAYGROUND=1
+
+### staging
+VITE_API_BASE_URL='https://app.develop.staging.example.com/api'
+VITE_SITE_URL='https://www.develop.staging.example.com'
+CYPRESS_API_BASE_URL='https://app.develop.staging.example.com/api'
+
+### debug:on,local
+DEBUG=1
+### debug:off,staging
+# DEBUG=
diff --git a/test_data/should_use_staging_db_in_local b/test_data/should_use_staging_db_in_local
new file mode 100644
index 0000000..8cb508a
--- /dev/null
+++ b/test_data/should_use_staging_db_in_local
@@ -0,0 +1,36 @@
+VITE_STRIPE_PK=
+VITE_SENTRY_ENABLED=
+VITE_SENTRY_DSN=
+### local,staging
+VITE_SENTRY_ENV=staging
+### prod
+# VITE_SENTRY_ENV=production
+
+### db:local
+# DATABASE_URL='postgres://user:password@localhost:5432/core'
+### db:staging
+DATABASE_URL='postgres://user:password@localhost:5555/core'
+### db:prod
+# DATABASE_URL='postgres://user:password@localhost:6666/core'
+
+CYPRESS_CRED_EMAIL='owner@cypress.test'
+CYPRESS_CRED_PASSWORD='12345678'
+CYPRESS_TEST_PRIVATE_TOKEN='12345678'
+
+### local
+VITE_API_BASE_URL='http://localhost:1337/api'
+VITE_SITE_URL='http://localhost:3000'
+CYPRESS_API_BASE_URL='http://localhost:1337/api'
+
+# this variable will not switch
+GRAPHQL_PLAYGROUND=1
+
+### staging
+# VITE_API_BASE_URL='https://app.develop.staging.example.com/api'
+# VITE_SITE_URL='https://www.develop.staging.example.com'
+# CYPRESS_API_BASE_URL='https://app.develop.staging.example.com/api'
+
+### debug:on,local
+DEBUG=1
+### debug:off,staging
+# DEBUG=