Drop temp table if it exists - sql

Question

Friends,
I am creating a temp table. The script may be run several times so I need to check if the temp table exist then drop it. I have the written the code below but I get an error when running the script twice, that the table already exists:
There is already an object named '#lu_sensor_name_19' in the database.
It appears that IF OBJECT_ID('alarm..#lu_sensor_name_19') IS NOT NULL does not return true when the tablle is not null. What am I doing wrong?
IF OBJECT_ID('alarm..#lu_sensor_name_19') IS NOT NULL
BEGIN
DROP TABLE #lu_sensor_name_19
END
CREATE TABLE #lu_sensor_name_19(
sensorname_id int NOT NULL,
sensorname nvarchar(50) NOT NULL,
paneltype_id smallint NOT NULL,
panel_version_id int NULL,
prefix_allowed tinyint NOT NULL,
base_allowed tinyint NOT NULL,
suffix_allowed tinyint NOT NULL,
key_value int NULL,
sort_index int NULL,
device_allowed tinyint NOT NULL,
sensor_name_group_id smallint NOT NULL,
)

Answer 1

Temp #Tables are created in tempdb. Try this:
IF OBJECT_ID('tempdb..#lu_sensor_name_19') IS NOT NULL
BEGIN
DROP TABLE #lu_sensor_name_19
END
CREATE TABLE #lu_sensor_name_19...
SQL Server 2016 added the ability to do the drop in one line:
DROP TABLE IF EXISTS #lu_sensor_name_19
CREATE TABLE #lu_sensor_name_19...

Answer 2

Use this.
IF OBJECT_ID('tempdb.dbo.##myTempTable', 'U') IS NOT NULL
BEGIN
DROP TABLE ##myTempTable;
--DROP TABLE ##tempdb.dbo.myTempTable;
/* Above line commented out, because it generates warning:
"Database name 'tempdb' ignored, referencing object in tempdb.",
which is a pain in the neck if you are using a temp table to generate SQL code,
and want to print the code to the screen.*/
END;
GO
CREATE TABLE ##myTempTable(
FooBar nvarchar(128) not null,
);
And, in SQL Server 2016, you can write:
DROP TABLE IF EXISTS ##myTempTable