For the query above, the following recommendations will be helpful as part of the SQL tuning process. You'll find 3 sections below:
Description of the steps you can take to speed up the query.
The optimal indexes for this query, which you can copy and create in your database.
An automatically re-written query you can copy and execute in your database.
The optimization process and recommendations:
Avoid LIKE Searches With Leading Wildcard (query line: 7): The database will not use an index when using like searches with a leading wildcard (e.g. '%'). Although it's not always a satisfactory solution, please consider using prefix-match LIKE patterns (e.g. 'TERM%').
Avoid Selecting Unnecessary Columns (query line: 2): Avoid selecting all columns with the '*' wildcard, unless you intend to use them all. Selecting redundant columns may result in unnecessary performance degradation.
Create Optimal Indexes (modified query below): The recommended indexes are an integral part of this optimization effort and should be created before testing the execution duration of the optimized query.
Optimal indexes for this query:
ALTER TABLE `#Premises` ADD INDEX `premises_idx_id` (`ID`);
The optimized query:
#Premises AS Premises2
ON #Premises.Name LIKE '%' + Premises2.Name + '%'
#Premises.ID <> Premises2.ID