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having
A HAVING clause in SQL specifies that an SQL SELECT statement must only return rows where aggregate values meet the specified conditions.
HAVING and WHERE are often confused by beginners, but they serve different purposes. WHERE is taken into account at an earlier stage of a query execution, filtering the rows read from the tables. If a query contains GROUP BY, rows from the tables are grouped and aggregated. After the aggregating operation, HAVING is applied, filtering out the rows that don't match the specified conditions. Therefore, WHERE applies to data read from tables, and HAVING should only apply to aggregated data, which isn't known in the initial stage of a query.
To view the present condition formed by the GROUP BY clause, the HAVING clause is used.
I've had a spate of low pressure issues recently.
MWP @ about 17.5mb
Centrica engineers are a special breed but I couldn't take being told again that I was wrong so I asked the last one to prove the pressure was OK. The guy quite confidently passed me his basic u-gauge to confirm my digital one...
In Brief !!
About to purchase a 2 bed apartment that was let out for the last 2 years and the landlord has done a full refurb .
During a visit a neighbour came over as we left and informed us that The previous tenant had complained no Gas safe landlord cert was issued to her during her...
Recently they flushed the system and installed the valve and filters. It is open vented cold feed and vent are in airing cupboard. No sign of safety valve on boiler, I was taught 40 years you never fitted
valves on the primary circuit for obvious reasons, do i tell homeowner?
Hi. I am having a new kitchen designed and installed and need some advice about whether what I wish to do would work well enough.
Currently my freestanding washing machine is in the corner of my kitchen, next to an outside wall. The plumbing and standpipe are right next to it, so it all works...
There seems to be a big shortage of duel flow kitchen taps, I know the trend is towards combis but there is still a lot of flats/bungalows with poor hot water pressure which means you need a duel flow tap.
Any one got a good supplier of them?
Thanks
Hi everyone and I hope someone can help.
Five years ago I had a new central heating system installed with a Baxi Platinum 33 HE in a 10 year warranty. It is service by a Baxi Engineer every September and I never have to touch it.
Anyway, I had a new wet room installed in my small bathroom and...
Had to switch off an old fellas heating today as he had no fixed ventilation for warm air unit, tried to argue the benefits of letting him use it but was bashed with the letter of the 'law' by gassafe advisor.
I totally get the point but when does it become ok (no a requirement) to leave an 80+...
Hi, I have a two year old Ideal Instinct boiler that has been problematic for about a month with low pressure. A plumber came out twice and reset it and it seemed ok but its started loosing pressure again a couple of days ago. He has been back and blown something up in the boiler which he...
Hi everyone, I'm eagerly awaiting an art deco-looking bathroom to be fitted to replace the current, sadly cracked, crackled and generally knackered 100 year-old suite and have already gleaned many tips on here, by lurking over the past couple of months. So thanks again.
How do I remove my bath mixer tap regulator? Its quite thin compared to all the videos and photos ive seen of people removing theirs. I bought new female+male aerators but struggling to remove it from the bath tap. Im not sure because its rusted or what but it doesnt budge.
For a couple of months now the CH side of the boiler has been leaking water. It would leak for a couple of days and stop. Very intermittent, but very annoying when we get water dripping everywhere (so the system would depressure quite significantly). I have isolated the behaviour to a valve on...
Investigating a leak in bathroom through the ceiling earlier and didn't take long to get to the bottom of it unfortunately it's under the floor the pressure on the boiler won't rise at all... they've had a right nibble..
Hi Everyone!
I just need a bit of advice on balancing radiators after managing to get 1 cold rad working, i'm just a general DIY'er hence the need for professional feedback.
Initially i had 1 cold rad in Utility room toward rear of house, no matter what i did i could not get this to work, also...
Hello,
I am looking for some advice regarding my baxi duo tec 33 he A. For some reason the hot water works but when I turn off the tap it does not revert to heating mode and the hot water light stays on. I have replaced the diverter valve cartridge which was seriously knackered. However I am...
Maybe not the usual thing you might see on a forum, but I thought I would give it a shot. My Dad is having Chemo and needs a walk in shower fitted with a bit of tiling. We purchased the shower tray, surround, tiles etc and had a plumber who is a family friend lined up but he has had to pull out...
Just starting on a project that involves installing a new gas supply U40 2 inch job but the client already has a very old u16 supply which is piped from a remote meter box and underground steel pipe. The pipework cannot deal with the increase in demand required (quite frankly its not really up...
Hi guys. I am after a bit of advice. I installed an Intergas boiler a couple of yrs ago. The client called me and said it kept cutting out so I told her to call Intergas. Intergas came and fitted a new gas valve but labelled the boiler At Risk for having no isolation valve at the appliance. He...
We're in the middle of a drought with 'day zero' estimated around May next year so I've decided to go off grid, or partially off grid in an effort to ensure I still have water at home.
I decided to use my borehole water for most of the house and just use council water for human consumption such...
I have now contacted 3 different gas engineers by either email or web form asking for a quote for a job at my daughter's house in East Bowling, Bradford. On all 3 occasions I have had no reply from the business I contacted. In fairness, I have had the same (lack of) response for requests for...
Well as the title suggests i'm looking to train to become a plumber in the Nottingham area.
Having done various other jobs i have now decided to have a complete career change and would welcome any advice anyone would be able to offer me.
Having trudged through the internet i am still no...
JasAsh1987
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