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Overview
| Comment: | Documentation on the new SQLITE_DBCONFIG options. |
|---|---|
| Timelines: | family | ancestors | descendants | both | new-dbconfig-options |
| Files: | files | file ages | folders |
| SHA3-256: |
4ebc1051c22d1dbd9b670c3c70cf730f |
| User & Date: | drh 2019-06-15 15:24:54 |
Context
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2019-06-17
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| 13:56 | Track the revised DQS interface. Closed-Leaf check-in: 09cea3924b user: drh tags: new-dbconfig-options | |
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2019-06-15
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| 15:24 | Documentation on the new SQLITE_DBCONFIG options. check-in: 4ebc1051c2 user: drh tags: new-dbconfig-options | |
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2019-06-12
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| 20:31 | Fix the description of how collation is computed to indicate that the collation is not blocked by a CAST operator. Fix for ticket https://www.sqlite.org/src/info/b148fa61059fb6c2. check-in: 9f887f15e5 user: drh tags: trunk | |
Changes
Changes to pages/lang.in.
119 119 RecursiveBubbleDiagram alter-table-stmt 120 120 </tcl> 121 121 122 122 <p>SQLite supports a limited subset of ALTER TABLE. 123 123 The ALTER TABLE command in SQLite allows the user to rename a table, 124 124 to rename a column within a table, or to add a new column to an existing table. 125 125 126 -<tcl>hd_fragment altertabrename {ALTER TABLE RENAME} {rename table}</tcl> 126 +<tcl>hd_fragment altertabrename {ALTER TABLE RENAME} {rename table} \ 127 + {ALTER TABLE RENAME documentation}</tcl> 127 128 <h3>ALTER TABLE RENAME</h3> 128 129 129 130 <p> ^(The RENAME TO syntax changes the name of <yyterm>table-name</yyterm> 130 131 to <yyterm>new-table-name</yyterm>.)^ 131 132 This command 132 133 cannot be used to move a table between attached databases, only to rename 133 134 a table within the same database. ................................................................................ 138 139 <b>Compatibility Note:</b> 139 140 The behavior of ALTER TABLE when renaming a table was enhanced 140 141 in versions 3.25.0 ([dateof:3.25.0]) and 3.26.0 ([dateof:3.26.0]) 141 142 in order to carry the rename operation forward into triggers and 142 143 views that reference the renamed table. This is considered an 143 144 improvement. Applications that depend on the older (and 144 145 arguably buggy) behavior can use the 145 -[PRAGMA legacy_alter_table=ON] statement to make ALTER TABLE RENAME 146 +[PRAGMA legacy_alter_table=ON] statement or the 147 +[SQLITE_DBCONFIG_LEGACY_ALTER_TABLE] configuration parameter 148 +on [sqlite3_db_config()] interface to make ALTER TABLE RENAME 146 149 behave as it did prior to version 3.25.0. 147 150 </blockquote> 148 151 149 152 <p> 150 153 Beginning with release 3.25.0 ([dateof:3.25.0]), references to the table 151 154 within trigger bodies and view definitions are also renamed. 152 155 </p>
Changes to pages/pragma.in.
816 816 contain code that expect the incomplete behavior 817 817 of [ALTER TABLE RENAME] found in older versions of SQLite. 818 818 New applications should leave this flag turned off. 819 819 <p>For compatibility with older [virtual table] implementations, 820 820 this flag is turned on temporarily while the [sqlite3_module.xRename] 821 821 method is being run. The value of this flag is restore after the 822 822 [sqlite3_module.xRename] method finishes. 823 + <p>The legacy alter table behavior can also be toggled on and off 824 + using the [SQLITE_DBCONFIG_LEGACY_ALTER_TABLE] option to the 825 + [sqlite3_db_config()] interface. 823 826 } 824 827 825 828 Pragma legacy_file_format { 826 829 <p>^(<b>PRAGMA legacy_file_format; 827 830 <br>PRAGMA legacy_file_format = <i>boolean</i></b></p> 828 831 <p>This pragma sets or queries the value of the legacy_file_format 829 832 flag.)^ ^(When this flag is on, new SQLite databases are created in
Changes to pages/quirks.in.
232 232 [http://site.icu-project.org/|International Components for Unicode] 233 233 library. 234 234 235 235 <tcl>hd_fragment dblquote {double-quoted string literal}</tcl> 236 236 <h1>Double-quoted String Literals Are Accepted</h1> 237 237 238 238 <p> 239 -The SQL standard says that one should use double-quotes around identifiers 240 -and single-quotes around string literals. 239 +The SQL standard requires double-quotes around identifiers 240 +and single-quotes around string literals. For example: 241 241 <ul> 242 242 <li> <tt>"this is a legal SQL column name"</tt> 243 243 <li> <tt>'this is an SQL string literal'</tt> 244 244 </ul> 245 245 <p> 246 246 SQLite accepts both of the above. But, in an effort to be compatible 247 -with MySQL 3.x (which was very popular when SQLite was first being 248 -designed) SQLite will also use content contained in double-quotes as a s 249 -tring literal if the content does not match any valid identifier. 247 +with MySQL 3.x (which was probably the most widely used RDBMS 248 +when SQLite was first being designed) SQLite will also use 249 +a double-quotes string as 250 +string literal if it does not match any valid identifier. 250 251 <p> 251 -An unfortunate side-effect of this is that a misspelled double-quoted 252 +This misfeature means that a misspelled double-quoted 252 253 identifier will be interpreted as a string literal, rather than generating 253 254 an error. 254 -Another problem is that this behavior allows developers who are new to 255 -the SQL language to continue using double-quoted string literals when they 255 +It also lures developers who are new to the SQL language into 256 +bad habit of using double-quoted string literals when they 256 257 really need to learn to use the correct single-quoted string literal form. 257 258 <p> 258 259 In hindsight, we should not have tried to make SQLite accept MySQL 3.x 259 260 syntax, and should have never allowed double-quoted string literals. 260 -However, we continue to support that capability to avoid breaking legacy 261 -applications. 261 +However, there are countless applications that make use of 262 +double-quoted string literals and so we continue to support 263 +that capability to avoid breaking legacy. 262 264 <p> 263 -Update: As of SQLite 3.27.0 ([dateof:3.27.0]) the use of a double-quoted 265 +Updates: 266 +<ul> 267 +<li><p> As of SQLite 3.27.0 ([dateof:3.27.0]) the use of a double-quoted 264 268 string literal causes a warning message to be sent to the [error log]. 269 +<li><p> As of SQLite 3.29.0 ([dateof:3.29.0]) the use of double-quoted 270 +string literals inside of DDL statements ([CREATE TABLE], [CREATE INDEX], 271 +and so forth) is disallowed and will cause a syntax error. Double quoted 272 +strings needed to be deactivated in DDL statements as they were causing 273 +problems for [ALTER TABLE]. 274 +(See the ticket at [https://www.sqlite.org/src/info/9b78184be266f] for 275 +details.) 276 +If needed for compatibility, the older behavior can be restored by 277 +disabling the [SQLITE_DBCONFIG_NO_DQS_SCHEMA] option on the 278 +[sqlite3_db_config()] interface. 279 +<li><p> The [SQLITE_DBCONFIG_NO_DQS] option the [sqlite3_db_config()] 280 +interface is available as of SQLite 3.29.0 ([dateof:3.29.0]) and can be 281 +used to disable double-quoted string literals in all contexts. 282 +This setting is currently off by default, but might default on in future 283 +releases of SQLite. Developers are encouraged to turn this setting on 284 +now, in preparation for the future when it might be activated by default. 285 +</ul> 265 286 266 287 <h1>Keywords Can Often Be Used As Identifiers</h1> 267 288 268 289 <p> 269 290 The SQL language is rich in keywords. 270 291 Most SQL implementations do not allow keywords to be used as identifiers 271 292 (the names of table or columns) unless they are enclosed in double-quotes.