Fixes #570 - Updated Postgres examples (#579)

* Fixes #570 - Updated Postgres examples

* Updated postgres crate to 0.17.2

Co-authored-by: Andrew Gauger <andygauge@gmail.com>

Cargo.toml

@@ -35,7 +35,7 @@ num = "0.2"
 num_cpus = "1.8"
 percent-encoding = "2.1"
 petgraph = "0.4"
-postgres = "0.15"
+postgres = "0.17.2"
 rand = "0.7.3"
 rand_distr = "0.2.2"
 rayon = "1.0"

src/database/postgres/aggregate_data.md

@@ -6,7 +6,7 @@ This recipe lists the nationalities of the first 7999 artists in the database of
 
 ```rust,no_run
 extern crate postgres;
-use postgres::{Connection, Error, TlsMode};
+use postgres::{Client, Error, NoTls};
 
 struct Nation {
     nationality: String,
@@ -14,12 +14,12 @@ struct Nation {
 }
 
 fn main() -> Result<(), Error> {
-    let conn = Connection::connect(
+    let mut client = Client::connect(
         "postgresql://postgres:postgres@127.0.0.1/moma",
-        TlsMode::None,
+        NoTls,
     )?;
 
-    for row in &conn.query 
+    for row in client.query 
 	("SELECT nationality, COUNT(nationality) AS count 
 	FROM artists GROUP BY nationality ORDER BY count DESC", &[])? {
         

src/database/postgres/create_tables.md

@@ -4,33 +4,36 @@
 
 Use the [`postgres`] crate to create tables in a Postgres database.
 
-[`Connection::connect`] helps in connecting to an existing database. The recipe uses a URL string format with `Connection::connect`. It assumes an existing database named `library`, the username is `postgres` and the password is `postgres`.
+[`Client::connect`] helps in connecting to an existing database. The recipe uses a URL string format with `Client::connect`. It assumes an existing database named `library`, the username is `postgres` and the password is `postgres`.
 
 ```rust,no_run
 extern crate postgres;
 
-use postgres::{Connection, TlsMode, Error};
+use postgres::{Client, NoTls, Error};
 
 fn main() -> Result<(), Error> {
-    let conn = Connection::connect("postgresql://postgres:postgres@localhost/library", 
-                                    TlsMode::None)?;
+    let mut client = Client::connect("postgresql://postgres:postgres@localhost/library", NoTls)?;
     
-     conn.execute("CREATE TABLE IF NOT EXISTS author (
+    client.batch_execute("
+        CREATE TABLE IF NOT EXISTS author (
             id              SERIAL PRIMARY KEY,
             name            VARCHAR NOT NULL,
             country         VARCHAR NOT NULL
-                  )", &[])?;
+            )
+    ")?;
 
-    conn.execute("CREATE TABLE IF NOT EXISTS book  (
+    client.batch_execute("
+        CREATE TABLE IF NOT EXISTS book  (
             id              SERIAL PRIMARY KEY,
             title           VARCHAR NOT NULL,
             author_id       INTEGER NOT NULL REFERENCES author
-                )", &[])?;
+            )
+    ")?;
 
     Ok(())
 
 }
 ```
 
-[`postgres`]: https://docs.rs/postgres/0.15.2/postgres/
-[`Connection::connect`]: https://docs.rs/postgres/0.15.2/postgres/struct.Connection.html#method.connect
+[`postgres`]: https://docs.rs/postgres/0.17.2/postgres/
+[`Client::connect`]: https://docs.rs/postgres/0.17.2/postgres/struct.Client.html#method.connect

src/database/postgres/insert_query_data.md

@@ -2,12 +2,12 @@
 
 [![postgres-badge]][postgres] [![cat-database-badge]][cat-database]
 
-The recipe inserts data into the `author` table using [`execute`] method of `Connection`. Then, displays the data from the `author` table  using [`query`] method of `Connection`.
+The recipe inserts data into the `author` table using [`execute`] method of `Client`. Then, displays the data from the `author` table  using [`query`] method of `Client`.
 
 ```rust,no_run
 extern crate postgres;
 
-use postgres::{Connection, TlsMode, Error};
+use postgres::{Client, NoTls, Error};
 use std::collections::HashMap;
 
 struct Author {
@@ -17,8 +17,8 @@ struct Author {
 }
 
 fn main() -> Result<(), Error> {
-    let conn = Connection::connect("postgresql://postgres:postgres@localhost/library", 
-                                    TlsMode::None)?;
+    let mut client = Client::connect("postgresql://postgres:postgres@localhost/library", 
+                                    NoTls)?;
     
     let mut authors = HashMap::new();
     authors.insert(String::from("Chinua Achebe"), "Nigeria");
@@ -32,11 +32,13 @@ fn main() -> Result<(), Error> {
             country: value.to_string()
         };
 
-        conn.execute("INSERT INTO author (name, country) VALUES ($1, $2)",
-                 &[&author.name, &author.country])?;
+        client.execute(
+                "INSERT INTO author (name, country) VALUES ($1, $2)",
+                &[&author.name, &author.country],
+        )?;
     }
 
-    for row in &conn.query("SELECT id, name, country FROM author", &[])? {
+    for row in client.query("SELECT id, name, country FROM author", &[])? {
         let author = Author {
             _id: row.get(0),
             name: row.get(1),
@@ -50,5 +52,5 @@ fn main() -> Result<(), Error> {
 }
 ```
 
-[`execute`]: https://docs.rs/postgres/0.15.2/postgres/struct.Connection.html#method.execute
-[`query`]: https://docs.rs/postgres/0.15.2/postgres/struct.Connection.html#method.query
+[`execute`]: https://docs.rs/postgres/0.17.2/postgres/struct.Client.html#method.execute
+[`query`]: https://docs.rs/postgres/0.17.2/postgres/struct.Client.html#method.query