What is Boolean Search?
According to the New York Public Library:
Boolean searching is built on a method of symbolic logic developed by George Boole, a 19th century English mathematician. Boolean searches allow you to combine words and phrases using the words AND, OR, NOT (known as Boolean operators) to limit, broaden, or define your search.
The word “Boolean” comes from the man who invented Boolean Logic in the 19th century – George Boole.
Boolean Logic is the basis of modern computer logic, and George Boole is regarded in hindsight as one of the founders of the field of computer science.
To help you better understand what this means, think about how you would normally search for something on the Internet.
If you are looking for cars, the word cars will go into the search box.
What if you wish to search for burgers and fries?
Boolean search will allow you to get those results by entering burgers and fries into the search box.
Boolean search is a very powerful way to find exactly what you want online.
And there are a few Boolean tricks that every recruiter should know of to make their life easier.
Where Can I Use Boolean?
Boolean is a wide accepted form of search string.
Commonly you could use them in the search engine of job boards.
LinkedIN also allows Boolean searches on their site.
I dare say any website with a search box would permit and accept the use of Boolean search strings.
Before I go into the tricks I’ve learned let’s look at all the basic Boolean strings you could piece together.
Why Boolean Works
The basis of this is that you will list down what you have.
If you are a Java developer, chances of the word Java appearing in your profile would be high.
So if I’m looking for a Java Developer, the chance of me coming across your profile would be equally high.
You can see an assumption here – that the candidate would have the keyword in his/her profile if it is relevant.
Boolean Search Basics
Before I could touch on the Boolean tricks, you need to understand the basics.
And that would begin with the Operators.
Operators are the words that limit, broaden and define your search.
Let’s take a look at the available Boolean operators that you could use:
This is used if you wish to find a result that carries a combination of items.
So if you wish to find a search results that contain both Burgers and Fries, your search string would look simply like this:
Burgers AND Fries
This would be used if you are trying to find results that could contain either of the things you are looking for.
So if your search criteria could accept results that contain either Burgers or Fries, your search string would look like this:
Burgers OR Fries
This operator comes in when you wish to retrieve search results that doesn’t contain specific keywords.
So let’s say you just want to see burger and not french fries, your search string would look like this:
Burgers NOT “French Fries”
Some search engine might require you to put an AND before NOT:
Burgers AND NOT “French Fries”
Experiment a little to find out what is acceptable by the search engine.
4. Quotation Marks ” “
Some of you would have noticed I placed quotation marks before and after French Fries.
In Boolean terms, that is to tell the system that French Fries is a single keyword.
If that isn’t included, you would get search results with the keyword French and Fries as long as they appear in the profile and not necessarily in that specific sequence.
The quotation marks ensure search results carry the words in that specific order you entered.
In certain cases, you might not get any results as all because the search engine would interpret this as an incomplete search string.
So if you wish to search for Customer Service Manager, the term on your search string would look like this:
“Customer Service Manager”
5. Wild Card *
Because we can’t control how candidates would list their skills/jobs the way we like it to, we need to make sure all possible terms are applied to the search string.
Say you wish to find a profile with the keyword engineer.
For a candidate, they might not use that exact word. Instead, they might use engineering.
You could use the OR operator to ensure you cover both terms. But if you have more than 2 terms, it might be a bit of a hassle to construct.
A quicker way is to use a wildcard to search for spelling variations within the same or related terms:
This will return results with the keyword engineer or engineering.
6. Parentheses ()
Now we are getting a bit advanced.
When I was doing training for my agency recruiters, this is the part where most people would get confused.
Parentheses are used to separate phrases using the OR operator from the words or phrases using the AND operator.
So to give you an example, say you are looking for a programmer. He could be based in Singapore or Malaysia.
Given that a programmer might also be listed as a developer, you would want to include the word developer as well.
A typical newbie mistake would be to chain up something like these:
- Programmer OR developer OR Singapore OR Malaysia
- Programmer OR developer AND Singapore OR Malaysia
Now both search strings would return you with either nothing or not the results you are looking for.
The first one would return results with either of those keywords. It won’t be a specific search at all.
The second one would not be considered a complete search string and probably return with zero results.
That’s because the computer doesn’t know Programmer & Developer belong to one search set and Singapore & Malaysia in another.
To provide clarity, you need to put in brackets which we call Parentheses:
(Programmer OR developer) AND (Singapore OR Malaysia)
A Good Search Result
Boolean is more Skill than Science, and a recruiter’s experience and market knowledge influence greatly on the search outcome.
The same Boolean string you use today would probably yield you a different result tomorrow since there will be new data in the system.
To know if it is a right string, you could use the number of results as a gauge.
There are different school of thoughts but personally I feel a good number is around 50.
Anything more you might want to tighten up your search string; anything lesser than you loosen it.
Be Aware Of False Positive
Because Boolean focuses just on keywords, it won’t be able to identify the meaning behind those words.
So if you are searching for a candidate with the term Managing Director because you are looking for one, there is the possibility that the Secretary to Managing Director would come up as well.
Be Mindful Of Synonyms
Customer Service Manager
Customer Service Mgr
They all mean the same thing. But if you only pick one for your search string, you would be missing out on some good candidates who’s vocabulary differ from yours.
Know the common synonyms that would refer to the same thing and use a parentheses to make sure all are considered.
Yes, I know.
Boolean isn’t the most interesting read. Chances are you have bounced off to your Facebook and Instagram a dozen times before reaching to this paragraph.
But it is crucial so you can save time in future sourcing and help you reach out to the right audience.
As the world of recruitment gets more and more competitive, all these would be significant to ensure you get an edge and be ahead.
Unfortunately, what I covered earlier would also put you on par with many recruiters and sourcers who could pull together effective search strings in their sleep.
To get ahead, you need to level up and go onto the expert level.
Advanced Boolean Tips And Tricks
We learned earlier on the individual operators and how they work.
But they would only allow you to skim the surface.
If you want to deep dive into a specific target audience (and you should), it would require using as many available operators as possible and chain them into one single search string.
Let’s look at the following real life example. This is a job posting put up by StarHub.
Manager, Telco Network Security
To plan, lead, manage and organize the security operations in protecting StarHub’s enterprise and telco engineering networks.
- Lead teams to deploy and operate Identity Management (IDM), Mobile Device Management (MDM) and Enterprise Single Sign-On (ESSO) solutions/ systems
- Implement systems/ solutions to ensure business and security compliance in Payment Card industry Data Security Standard (PCI DSS), Regulatory and Cyber Security
- Coordinate internal and external audit to ensure business processes and security policies are in place to govern the operations
- Implement security applications and solutions (Firewall, IDS, IPS, email security, End-point protection, etc) to protect the StarHub enterprise and Telco engineering networks
- Engage external MSS provider to provide security monitoring and alert for both the enterprise and Telco engineering networks
- Conduct penetration test on new networks or services before launch, and ensure the company complies with the standards and guidelines stipulated by the regulators and systems
- At least 8 years of relevant working experiences in a fast-paced, large scale IT security projects or operations environment
- Extensive knowledge of networking and network security products, technologies, and protocols.
- Up-to-date knowledge of current vulnerabilities, attacks and counter-measures, as well as all security related news and developments
- Relevant professional security certifications would be advantageous (CISSP, CISM etc)
- Hands-on leadership with high level of discernment in dealing with emergency and/or tense situations
For an initial search, my advice is to be as specific as possible. After that, you go as wide as possible.
Let’s look at a specific example first.
A search string I would possibly construct would look like this:
“Network Security” AND (CISSP OR CISM) AND emergency AND (Singtel OR M1) AND (Singaporean OR “Singapore citizen” OR “Singapore PR” OR “Singapore Permanent Resident”) NOT StarHub
Network security is the basis of the role so that exact keyword is a must.
There are way more security certifications out there then just CISSP and CISM. In an actual search, I would find out what they are and add them to my search string.
I felt emergency is a good addition as you would want someone who has fire-fighting experience, not just purely preventive experience.
When employers come to agency recruiters, it is expected that they want to hire people from their competitors.
They can’t do that directly because it would just lead to an all-out war.
So they find intermediaries to do the dirty work.
On the assumption, I added in the names of StarHub competitors in the hope that the results contained profiles who has worked or are working there right now.
StarHub as a keyword is omitted as I won’t want to look at the ex or existing staffs.
Finally, on the assumption that StarHub isn’t keen to apply for work passes, a set on nationality status is included to narrow down the search.
You might get what you are looking for, or nothing at all.
Boolean search structure is like your cooking recipe. If you follow it, you will get a certain set of consistent results.
But it depends on what you feed it with. If you use the wrong ingredients, you will end up with a funky dish.
So identification of the right keywords is crucial to your success. And that takes a lot of attempts and experimentation.
2. From Specific Locations
In some cases, you might have to look at candidates from a specific location only.
Probably because the workplace is on one end of the country so it doesn’t make sense to look at job seekers who are staying on the opposite end.
You could list down all the specific addresses around the target area but that would take you ages.
A quicker way is to make use of postal codes to cast your net accurately.
In Singapore, different sectors would have their unique postal codes. And the first two digits would provide the general location.
So if the postal code begins with 07 or 08, you are looking at Anson and Tanjong Pagar.
And you could include into your search string:
(“Singapore 07*” OR “Singapore 08*”)
So I’m telling the computer to display results which contained either:
- Singapore 07xxxx
- Singapore 08xxxx
The wild card is inserted to cater for any variation of the last 4 numbers.
And the quotation marks are to ensure the word Singapore would appear just before the postal codes, as how it would be constructed commonly by everyone.
Here’s a full list of postal codes for Singapore:
|Postal District||Postal Sector|
(1st 2 digits of 6-digit postal codes)
|01||01, 02, 03, 04, 05|
|02||07, 08||Anson, Tanjong Pagar|
|03||14, 15, 16||Queenstown, Tiong Bahru|
|04||09, 10||Telok Blangah, Harbourfront|
|05||11, 12, 13||Pasir Panjang, Hong Leong Garden, Clementi New Town|
|06||17||High Street, Beach Road (part)|
|07||18, 19||Middle Road, Golden Mile|
|08||20, 21||Little India|
|09||22, 23||Orchard, Cairnhill, River Valley|
|10||24, 25, 26, 27||Ardmore, Bukit Timah, Holland Road, Tanglin|
|11||28, 29, 30||Watten Estate, Novena, Thomson|
|12||31, 32, 33||Balestier, Toa Payoh, Serangoon|
|13||34, 35, 36, 37||Macpherson, Braddell|
|14||38, 39, 40, 41||Geylang, Eunos|
|15||42, 43, 44, 45||Katong, Joo Chiat, Amber Road|
|16||46, 47, 48||Bedok, Upper East Coast, Eastwood, Kew Drive|
|17||49, 50, 81||Loyang, Changi|
|18||51, 52||Simei, Tampines, Pasir Ris|
|19||53, 54, 55, 82||Serangoon Garden, Hougang, Ponggol|
|20||56, 57||Bishan, Ang Mo Kio|
|21||58, 59||Upper Bukit Timah, Clementi Park, Ulu Pandan|
|22||60, 61, 62, 63, 64||Jurong|
|23||65, 66, 67, 68||Hillview, Dairy Farm, Bukit Panjang, Choa Chu Kang|
|24||69, 70, 71||Lim Chu Kang, Tengah|
|25||72, 73||Kranji, Woodgrove, Woodlands|
|26||77, 78||Upper Thomson, Springleaf|
|27||75, 76||Yishun, Sembawang|
3. Convert a long list into a string
In my previous StarHub example, it was simple to add in their competitors into the search string because we know there are only 3 Telcos in Singapore.
But for many other industries, you would have dozens if not hundreds of competitors.
It would make sense putting those names into your search string so you could find people who are working in those companies but doing such a string set would probably take you an hour before you stab your eye with a fork.
There is a hack to put these together in less than 5 seconds.
To begin, fire up a word processor. In my example below, I use Microsoft Words 2016. But any other versions would work as well.
I took a random list of companies’ names from Singapore Manufacturing Association website and paste it into a word document.
Remove all inherited formatting.
Select the text you wish to convert in this exercise (or do a Ctrl-A) and hit the Replace button.
For the Find what box, key in: ^p
For the Replace with box, key in: ” OR ”
^p refers to the line breaks. Replacing the line breaks with ” OR “, you are getting rid of any line breaks and at the same time placing in quotation marks and the OR operator.
We are not done yet.
If you notice, the front end and the back end doesn’t come with quotation marks.
You need to manually fix that and you have a search string set of competitors.
This is also useful when you wish to find candidates from a long list of courses or universities.
Boolean can be complicated when you first begin but as you go along, you realized it is all logic and common sense.
It is simply a different kind of language that the computer could clearly understand so you could retrieve the set of data you are looking for.
I hope this would be helpful in helping you uncover the candidates you’ve been looking for.
Question: Do you have any other Boolean tricks that you’d found useful? You can also leave a comment below.