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| Comment: | Back out the previous change. We are instead going to modify the code to match the documentation. |
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e16ada80d643aa072ae0ce0daf8c3538 |
| User & Date: | drh 2019-08-05 20:39:24 |
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2019-08-07
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| 21:59 | Fix typo in comment. (check-in: b0c5406903 user: mistachkin tags: trunk) | |
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2019-08-05
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| 20:39 | Back out the previous change. We are instead going to modify the code to match the documentation. (check-in: 3578d6c47b user: drh tags: branch-3.29) | |
| 20:39 | Back out the previous change. We are instead going to modify the code to match the documentation. (check-in: e16ada80d6 user: drh tags: trunk) | |
| 12:54 | Update the documentation on the affinity of the columns of VIEWs and subqueries that are generated from expressions to match the actual implementation of 10 years standing - namely such columns have BLOB affinity, not no affinity. Ticket https://www.sqlite.org/src/info/d52a29a9e6bc55c5 (check-in: 07b7749da8 user: drh tags: trunk) | |
Changes to pages/datatype3.in.
312 312 313 313 <li><p>^Otherwise, an expression has no affinity. 314 314 </ul> 315 315 316 316 <tcl>hd_fragment affview {rules for determining column affinity in VIEWs}</tcl> 317 317 <h2>Column Affinity For Views And Subqueries</h2> 318 318 319 -<p>The columns of a [VIEW] or FROM-clause subquery have the same affinity 320 -as the expressions in the result set of the [SELECT] statement that implements the VIEW 321 -or subquery. Except, column of a VIEW or subquery that are generated by expressions 322 -that have no affinity are assigned an affinity of BLOB. 319 +<p>The "columns" of a [VIEW] or FROM-clause subquery are really 320 +the expressions 321 +in the result set of the [SELECT] statement that implements the VIEW 322 +or subquery. Thus, the affinity for columns of a VIEW or subquery 323 +are determined by the expression affinity rules above. 323 324 Consider an example: 324 325 325 326 <blockquote><pre> 326 327 CREATE TABLE t1(a INT, b TEXT, c REAL); 327 328 CREATE VIEW v1(x,y,z) AS SELECT b, a+c, 42 FROM t1 WHERE b!=11; 328 329 </pre></blockquote> 329 330 330 331 <p>The affinity of the v1.x column will be the same as the affinity 331 332 of t1.b (TEXT), since v1.x maps directly into t1.b. But 332 333 columns v1.y and v1.z both have no affinity, since those columns 333 334 map into expression a+c and 42, and expressions always have no 334 -affinity, so that v1.y and v1.z columns have an affinity of BLOB. 335 +affinity. 335 336 336 337 <p>When the [SELECT] statement that implements a [VIEW] or 337 338 FROM-clause subquery is a [compound SELECT] then the affinity of 338 339 each supposed column of the VIEW or subquery will 339 340 be the affinity of the corresponding result column for 340 341 one of the individual SELECT statements that make up 341 342 the compound.