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Ivan BlinkovandGitHub
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* CLICKHOUSE-4063: less manual html @ index.md * CLICKHOUSE-4063: recommend markdown="1" in README.md * CLICKHOUSE-4003: manually purge custom.css for now * CLICKHOUSE-4064: expand <details> before any print (including to pdf) * CLICKHOUSE-3927: rearrange interfaces/formats.md a bit * CLICKHOUSE-3306: add few http headers * Remove copy-paste introduced in #3392 * Hopefully better chinese fonts #3392 * get rid of tabs @ custom.css * Apply comments and patch from #3384 * Add jdbc.md to ToC and some translation, though it still looks badly incomplete * minor punctuation * Add some backlinks to official website from mirrors that just blindly take markdown sources * Do not make fonts extra light * find . -name '*.md' -type f | xargs -I{} perl -pi -e 's//g' {} * find . -name '*.md' -type f | xargs -I{} perl -pi -e 's/ sql/g' {} * Remove outdated stuff from roadmap.md * Not so light font on front page too * Refactor Chinese formats.md to match recent changes in other languages
1.4 KiB
1.4 KiB
Conditional functions
if(cond, then, else), cond ? operator then : else
Returns then if cond != 0, or else if cond = 0.
cond must be of type UInt8, and then and else must have the lowest common type.
then and else can be NULL
multiIf
Allows you to write the CASE operator more compactly in the query.
multiIf(cond_1, then_1, cond_2, then_2...else)
Parameters:
cond_N— The condition for the function to returnthen_N.then_N— The result of the function when executed.else— The result of the function if none of the conditions is met.
The function accepts 2N+1 parameters.
Returned values
The function returns one of the values then_N or else, depending on the conditions cond_N.
Example
Take the table
┌─x─┬────y─┐
│ 1 │ ᴺᵁᴸᴸ │
│ 2 │ 3 │
└───┴──────┘
Run the query SELECT multiIf(isNull(y) x, y < 3, y, NULL) FROM t_null. Result:
┌─multiIf(isNull(y), x, less(y, 3), y, NULL)─┐
│ 1 │
│ ᴺᵁᴸᴸ │
└────────────────────────────────────────────┘