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SQL X-to-Y

damirsystems.com

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Re: SQL X-to-Y

#12

Post by yamrzou »

gberger wrote: post #2

Why do I have to complete a captcha to access this website?

In addition, I find the new hCaptcha used by Cloudflare much worse than reCAPTCHA. It's slower, with ambiguous inputs demanding more mental effort, and sometimes it just refuses my correct answers.

Re: SQL X-to-Y

#13

Post by SPBS »

I find the notation compact but confusing. Are Thing and Category essentially tables? What does `thing {T, C}` mean, if T already means Thing?

Re: SQL X-to-Y

#14

Post by flotzam »

yamrzou wrote: post #12
gberger wrote: post #2

Why do I have to complete a captcha to access this website?

In addition, I find the new hCaptcha used by Cloudflare much worse than reCAPTCHA. It's slower, with ambiguous inputs demanding more mental effort, and sometimes it just refuses my correct answers.

Google probably has a good enough handle on you to serve the easy captchas. But keep in mind that for users they can't fingerprint (e.g. with Tor Browser), reCAPTCHA is usually insanely hard or even blocked ("Your computer or network may be sending automated queries"). hCaptcha has been heavenly compared to that.

Re: SQL X-to-Y

#15

Post by panda17 »

SPBS wrote: post #13

I find the notation compact but confusing. Are Thing and Category essentially tables? What does `thing {T, C}` mean, if T already means Thing?

A thing is uniquely identified by T, category by C.

May read it as: CREATE TABLE thing (T_ID integer, C_ID integer)

Re: SQL X-to-Y

#16

Post by mulmen »

Is there further discussion of the "Alternate Key" somewhere? This is a new term to me. Is it like a candidate key?

Re: SQL X-to-Y

#17

Post by mulmen »

taffer wrote: post #4

SQL Assertions are incidentally the most requested feature for the Oracle database: https://community.oracle.com/tech/apps-infra/discussion/4390...

/me mumbles something about the BOOLEAN data type.

Re: SQL X-to-Y

#18

Post by panda17 »

mulmen wrote: post #16

Is there further discussion of the "Alternate Key" somewhere? This is a new term to me. Is it like a candidate key?

In general there can be more than one candidate key for a given relation (table). Only one candidate key is "primary", all others are "alternate".

Re: SQL X-to-Y

#19

Post by kthejoker2 »

mulmen wrote: post #16

Is there further discussion of the "Alternate Key" somewhere? This is a new term to me. Is it like a candidate key?

Yes, it is exactly a candidate key as they describe it - simply another field which uniquely identifies rows in the entity.

EDIT: Agree with panda17, they're using it as "candidate keys which were not chosen as primary key."

Re: SQL X-to-Y

#20

Post by bigbubba »

flotzam wrote: post #14
yamrzou wrote: post #12

Earlier quoted context omitted.

In addition, I find the new hCaptcha used by Cloudflare much worse than reCAPTCHA. It's slower, with ambiguous inputs demanding more mental effort, and sometimes it just refuses my correct answers.

Google probably has a good enough handle on you to serve the easy captchas. But keep in mind that for users they can't fingerprint (e.g. with Tor Browser), reCAPTCHA is usually insanely hard or even blocked ("Your computer or network may be sending automated queries"). hCaptcha has been heavenly compared to that.

'Hard' is not quite the right word for it. reCAPTCHA frequently rejects objectively correct responses when they fail to fingerprint you.
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