From 3f4949019db43c6229a199be1d006f7a3f92a602 Mon Sep 17 00:00:00 2001
From: Paulo Pires <pjpires@gmail.com>
Date: Mon, 21 Dec 2015 09:34:40 +0000
Subject: [PATCH 1/2] USE databasename will work only for existing databases.
 Fixes #5174

---
 cmd/influx/cli/cli.go | 37 +++++++++++++++++++++++++++++++++++--
 1 file changed, 35 insertions(+), 2 deletions(-)

diff --git a/cmd/influx/cli/cli.go b/cmd/influx/cli/cli.go
index b83505ceb4f..b936f11459f 100644
--- a/cmd/influx/cli/cli.go
+++ b/cmd/influx/cli/cli.go
@@ -322,8 +322,41 @@ func (c *CommandLine) use(cmd string) {
 		return
 	}
 	d := args[1]
-	c.Database = d
-	fmt.Printf("Using database %s\n", d)
+
+	// validate if specified database exists
+	query := "SHOW DATABASES"
+	response, err := c.Client.Query(client.Query{Command: query})
+	if err != nil {
+		fmt.Printf("ERR: %s\n", err)
+		return
+	}
+
+	if err := response.Error(); err != nil {
+		fmt.Printf("ERR: %s\n", err)
+		return
+	}
+
+	// verify the provided database exists
+	databaseExists := false
+	for _, result := range response.Results {
+		for _, row := range result.Series {
+			if row.Name == "databases" {
+				for _, values := range row.Values {
+					for _, database := range values {
+						if database == d {
+							databaseExists = true
+						}
+					}
+				}
+			}
+		}
+	}
+	if databaseExists {
+		c.Database = d
+		fmt.Printf("Using database %s\n", d)
+	} else {
+		fmt.Printf("ERR: Database %s doesn't exist. Run SHOW DATABASES for a list of existing databases.\n", d)
+	}
 }
 
 // SetPrecision sets client precision

From 3165c707fc4b87ac3101da97604b5e8f691931b3 Mon Sep 17 00:00:00 2001
From: Paulo Pires <pjpires@gmail.com>
Date: Tue, 22 Dec 2015 08:55:32 +0000
Subject: [PATCH 2/2] Small improvements to USE command as per PR comments.

---
 cmd/influx/cli/cli.go | 23 ++++++++++++-----------
 1 file changed, 12 insertions(+), 11 deletions(-)

diff --git a/cmd/influx/cli/cli.go b/cmd/influx/cli/cli.go
index b936f11459f..e84ebd95e40 100644
--- a/cmd/influx/cli/cli.go
+++ b/cmd/influx/cli/cli.go
@@ -324,8 +324,7 @@ func (c *CommandLine) use(cmd string) {
 	d := args[1]
 
 	// validate if specified database exists
-	query := "SHOW DATABASES"
-	response, err := c.Client.Query(client.Query{Command: query})
+	response, err := c.Client.Query(client.Query{Command: "SHOW DATABASES"})
 	if err != nil {
 		fmt.Printf("ERR: %s\n", err)
 		return
@@ -337,20 +336,22 @@ func (c *CommandLine) use(cmd string) {
 	}
 
 	// verify the provided database exists
-	databaseExists := false
-	for _, result := range response.Results {
-		for _, row := range result.Series {
-			if row.Name == "databases" {
-				for _, values := range row.Values {
-					for _, database := range values {
-						if database == d {
-							databaseExists = true
+	databaseExists := func() bool {
+		for _, result := range response.Results {
+			for _, row := range result.Series {
+				if row.Name == "databases" {
+					for _, values := range row.Values {
+						for _, database := range values {
+							if database == d {
+								return true
+							}
 						}
 					}
 				}
 			}
 		}
-	}
+		return false
+	}()
 	if databaseExists {
 		c.Database = d
 		fmt.Printf("Using database %s\n", d)