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Overview
Comment:Fix the sqlite3_table_column_metadata() routine so that it gives the correct answer for the "rowid" column in a WITHOUT ROWID table. Enhance it so that it can be used to check for the existence of a table by setting the column name parameter to NULL. The routine is now included in the build by default, even without the SQLITE_ENABLE_COLUMN_METADATA compile-time option.
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SHA1: cf9be419a16156a9814e1378bb49b780de977343
User & Date: drh 2014-12-09 22:24:42
Context
2014-12-10
04:58
Fix typos in the documentation for sqlite3_table_column_metadata(). No changes to code. check-in: 3528f8dd user: drh tags: trunk
2014-12-09
22:24
Fix the sqlite3_table_column_metadata() routine so that it gives the correct answer for the "rowid" column in a WITHOUT ROWID table. Enhance it so that it can be used to check for the existence of a table by setting the column name parameter to NULL. The routine is now included in the build by default, even without the SQLITE_ENABLE_COLUMN_METADATA compile-time option. check-in: cf9be419 user: drh tags: trunk
20:13
Add extra tests to e_walckpt.test. check-in: 84f95810 user: dan tags: trunk
Changes
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Changes to src/main.c.

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  pTab = sqlite3FindTable(db, zTableName, zDbName);
  if( !pTab || pTab->pSelect ){
    pTab = 0;
    goto error_out;
  }

  /* Find the column for which info is requested */
  if( sqlite3IsRowid(zColumnName) ){
    iCol = pTab->iPKey;
    if( iCol>=0 ){
      pCol = &pTab->aCol[iCol];
    }
  }else{
    for(iCol=0; iCol<pTab->nCol; iCol++){
      pCol = &pTab->aCol[iCol];
      if( 0==sqlite3StrICmp(pCol->zName, zColumnName) ){
        break;
      }
    }
    if( iCol==pTab->nCol ){




      pTab = 0;
      goto error_out;

    }
  }

  /* The following block stores the meta information that will be returned
  ** to the caller in local variables zDataType, zCollSeq, notnull, primarykey
  ** and autoinc. At this point there are two possibilities:
  ** 







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  pTab = sqlite3FindTable(db, zTableName, zDbName);
  if( !pTab || pTab->pSelect ){
    pTab = 0;
    goto error_out;
  }

  /* Find the column for which info is requested */
  if( zColumnName==0 ){
    /* Query for existance of table only */



  }else{
    for(iCol=0; iCol<pTab->nCol; iCol++){
      pCol = &pTab->aCol[iCol];
      if( 0==sqlite3StrICmp(pCol->zName, zColumnName) ){
        break;
      }
    }
    if( iCol==pTab->nCol ){
      if( HasRowid(pTab) && sqlite3IsRowid(zColumnName) ){
        iCol = pTab->iPKey;
        pCol = iCol>=0 ? &pTab->aCol[iCol] : 0;
      }else{
        pTab = 0;
        goto error_out;
      }
    }
  }

  /* The following block stores the meta information that will be returned
  ** to the caller in local variables zDataType, zCollSeq, notnull, primarykey
  ** and autoinc. At this point there are two possibilities:
  ** 

Changes to src/sqlite.h.in.

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*/
SQLITE_DEPRECATED void sqlite3_soft_heap_limit(int N);


/*
** CAPI3REF: Extract Metadata About A Column Of A Table
**
** ^This routine returns metadata about a specific column of a specific
** database table accessible using the [database connection] handle
** passed as the first function argument.








**
** ^The column is identified by the second, third and fourth parameters to
** this function. ^The second parameter is either the name of the database
** (i.e. "main", "temp", or an attached database) containing the specified
** table or NULL. ^If it is NULL, then all attached databases are searched
** for the table using the same algorithm used by the database engine to
** resolve unqualified table references.
**
** ^The third and fourth parameters to this function are the table and column
** name of the desired column, respectively. Neither of these parameters
** may be NULL.
**
** ^Metadata is returned by writing to the memory locations passed as the 5th
** and subsequent parameters to this function. ^Any of these arguments may be
** NULL, in which case the corresponding element of metadata is omitted.
**
** ^(<blockquote>
** <table border="1">
................................................................................
** <tr><td> 7th <td> int         <td> True if column has a NOT NULL constraint
** <tr><td> 8th <td> int         <td> True if column is part of the PRIMARY KEY
** <tr><td> 9th <td> int         <td> True if column is [AUTOINCREMENT]
** </table>
** </blockquote>)^
**
** ^The memory pointed to by the character pointers returned for the
** declaration type and collation sequence is valid only until the next
** call to any SQLite API function.
**
** ^If the specified table is actually a view, an [error code] is returned.
**
** ^If the specified column is "rowid", "oid" or "_rowid_" and an

** [INTEGER PRIMARY KEY] column has been explicitly declared, then the output
** parameters are set for the explicitly declared column. ^(If there is no
** explicitly declared [INTEGER PRIMARY KEY] column, then the output
** parameters are set as follows:
**
** <pre>
**     data type: "INTEGER"
**     collation sequence: "BINARY"
**     not null: 0
**     primary key: 1
**     auto increment: 0
** </pre>)^
**
** ^(This function may load one or more schemas from database files. If an
** error occurs during this process, or if the requested table or column
** cannot be found, an [error code] is returned and an error message left
** in the [database connection] (to be retrieved using sqlite3_errmsg()).)^
*/
int sqlite3_table_column_metadata(
  sqlite3 *db,                /* Connection handle */
  const char *zDbName,        /* Database name or NULL */
  const char *zTableName,     /* Table name */
  const char *zColumnName,    /* Column name */
  char const **pzDataType,    /* OUTPUT: Declared data type */







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*/
SQLITE_DEPRECATED void sqlite3_soft_heap_limit(int N);


/*
** CAPI3REF: Extract Metadata About A Column Of A Table
**
** ^The sqlite3_table_column_metadata(X,D,T,C,....) routine returns
** information about column C of table T in database D
** on [database connection] X.  ^The sqlite3_table_column_metadata()
** interface returns SQLITE_OK and fills in the non-NULL pointers in
** the final five arguments with appropriate vaules if the specified
** column exists.  ^The sqlite3_table_column_metadata() interface returns
** SQLITE_ERROR and if the specified column does not exist.
** If the column-name parameter to sqlite3_table_column_metadata() is a
** NULL pointer, then the routine simply checks for the existance of the
** table and returns SQLITE_OK if the table exists and SQLITE_ERROR if it
** does not.
**
** ^The column is identified by the second, third and fourth parameters to
** this function. ^The second parameter is either the name of the database
** (i.e. "main", "temp", or an attached database) containing the specified
** table or NULL. ^If it is NULL, then all attached databases are searched
** for the table using the same algorithm used by the database engine to
** resolve unqualified table references.
**
** ^The third and fourth parameters to this function are the table and column
** name of the desired column, respectively.

**
** ^Metadata is returned by writing to the memory locations passed as the 5th
** and subsequent parameters to this function. ^Any of these arguments may be
** NULL, in which case the corresponding element of metadata is omitted.
**
** ^(<blockquote>
** <table border="1">
................................................................................
** <tr><td> 7th <td> int         <td> True if column has a NOT NULL constraint
** <tr><td> 8th <td> int         <td> True if column is part of the PRIMARY KEY
** <tr><td> 9th <td> int         <td> True if column is [AUTOINCREMENT]
** </table>
** </blockquote>)^
**
** ^The memory pointed to by the character pointers returned for the
** declaration type and collation sequence is valid until the next
** call to any SQLite API function.
**
** ^If the specified table is actually a view, an [error code] is returned.
**
** ^If the specified column is "rowid", "oid" or "_rowid_" and the table 
** is not a [WITHOUT ROWID] table and an
** [INTEGER PRIMARY KEY] column has been explicitly declared, then the output
** parameters are set for the explicitly declared column. ^(If there is no
** [INTEGER PRIMARY KEY] column, then the outputs
** for the [rowid] are set as follows:
**
** <pre>
**     data type: "INTEGER"
**     collation sequence: "BINARY"
**     not null: 0
**     primary key: 1
**     auto increment: 0
** </pre>)^
**
** ^This function causes all database schemas to be read from disk and
** parsed, if that has not already been done, and returns an error if
** any errors are encountered while loading the schema.

*/
int sqlite3_table_column_metadata(
  sqlite3 *db,                /* Connection handle */
  const char *zDbName,        /* Database name or NULL */
  const char *zTableName,     /* Table name */
  const char *zColumnName,    /* Column name */
  char const **pzDataType,    /* OUTPUT: Declared data type */

Changes to src/test1.c.

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  const char *zDatatype;
  const char *zCollseq;
  int notnull;
  int primarykey;
  int autoincrement;

  if( objc!=5 ){
    Tcl_WrongNumArgs(interp, 1, objv, "DB dbname tblname colname");
    return TCL_ERROR;
  }
  if( getDbPointer(interp, Tcl_GetString(objv[1]), &db) ) return TCL_ERROR;
  zDb = Tcl_GetString(objv[2]);
  zTbl = Tcl_GetString(objv[3]);
  zCol = Tcl_GetString(objv[4]);

  if( strlen(zDb)==0 ) zDb = 0;

  rc = sqlite3_table_column_metadata(db, zDb, zTbl, zCol, 
      &zDatatype, &zCollseq, &notnull, &primarykey, &autoincrement);

  if( rc!=SQLITE_OK ){







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  const char *zDatatype;
  const char *zCollseq;
  int notnull;
  int primarykey;
  int autoincrement;

  if( objc!=5 && objc!=4 ){
    Tcl_WrongNumArgs(interp, 1, objv, "DB dbname tblname colname");
    return TCL_ERROR;
  }
  if( getDbPointer(interp, Tcl_GetString(objv[1]), &db) ) return TCL_ERROR;
  zDb = Tcl_GetString(objv[2]);
  zTbl = Tcl_GetString(objv[3]);
  zCol = objc==5 ? Tcl_GetString(objv[4]) : 0;

  if( strlen(zDb)==0 ) zDb = 0;

  rc = sqlite3_table_column_metadata(db, zDb, zTbl, zCol, 
      &zDatatype, &zCollseq, &notnull, &primarykey, &autoincrement);

  if( rc!=SQLITE_OK ){

Changes to test/colmeta.test.

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# Set up a schema in the main and temp test databases.
do_test colmeta-0 {
  execsql {
    CREATE TABLE abc(a, b, c);
    CREATE TABLE abc2(a PRIMARY KEY COLLATE NOCASE, b VARCHAR(32), c);
    CREATE TABLE abc3(a NOT NULL, b INTEGER PRIMARY KEY, c);


  }
  ifcapable autoinc {
    execsql {
      CREATE TABLE abc4(a, b INTEGER PRIMARY KEY AUTOINCREMENT, c);
    }
  }
  ifcapable view {
................................................................................
  4  {main abc2 b}               {0 {VARCHAR(32) BINARY 0 0 0}}
  5  {{} abc2 a}                 {0 {{} NOCASE 0 1 0}}
  6  {{} abc3 a}                 {0 {{} BINARY 1 0 0}}
  7  {{} abc3 b}                 {0 {INTEGER BINARY 0 1 0}}
  13 {main abc rowid}            {0 {INTEGER BINARY 0 1 0}}
  14 {main abc3 rowid}           {0 {INTEGER BINARY 0 1 0}}
  16 {main abc d}                {1 {no such table column: abc.d}}








}
ifcapable view {
  set tests [concat $tests {
    8  {{} abc4 b}                 {0 {INTEGER BINARY 0 1 1}}
    15 {main abc4 rowid}           {0 {INTEGER BINARY 0 1 1}}
  }]
}
ifcapable view {
  set tests [concat $tests {
    9  {{} v1 a}                   {1 {no such table column: v1.a}}
    10 {main v1 b}                 {1 {no such table column: v1.b}}
    11 {main v1 badname}           {1 {no such table column: v1.badname}}
    12 {main v1 rowid}             {1 {no such table column: v1.rowid}}
  }]
}

foreach {tn params results} $tests {
  set ::DB [sqlite3_connection_pointer db]

  set tstbody [concat sqlite3_table_column_metadata $::DB $params] 
................................................................................

  set ::DB [sqlite3_connection_pointer db]
  set tstbody [concat sqlite3_table_column_metadata $::DB $params] 
  do_test colmeta-$tn.2 {
    list [catch $tstbody msg] [set msg]
  } $results
}












finish_test







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# Set up a schema in the main and temp test databases.
do_test colmeta-0 {
  execsql {
    CREATE TABLE abc(a, b, c);
    CREATE TABLE abc2(a PRIMARY KEY COLLATE NOCASE, b VARCHAR(32), c);
    CREATE TABLE abc3(a NOT NULL, b INTEGER PRIMARY KEY, c);
    CREATE TABLE abc5(w,x,y,z,PRIMARY KEY(x,z)) WITHOUT ROWID;
    CREATE TABLE abc6(rowid TEXT COLLATE rtrim, oid REAL, _rowid_ BLOB);
  }
  ifcapable autoinc {
    execsql {
      CREATE TABLE abc4(a, b INTEGER PRIMARY KEY AUTOINCREMENT, c);
    }
  }
  ifcapable view {
................................................................................
  4  {main abc2 b}               {0 {VARCHAR(32) BINARY 0 0 0}}
  5  {{} abc2 a}                 {0 {{} NOCASE 0 1 0}}
  6  {{} abc3 a}                 {0 {{} BINARY 1 0 0}}
  7  {{} abc3 b}                 {0 {INTEGER BINARY 0 1 0}}
  13 {main abc rowid}            {0 {INTEGER BINARY 0 1 0}}
  14 {main abc3 rowid}           {0 {INTEGER BINARY 0 1 0}}
  16 {main abc d}                {1 {no such table column: abc.d}}
  20 {main abc5 w}               {0 {{} BINARY 0 0 0}}
  21 {main abc5 x}               {0 {{} BINARY 1 1 0}}
  22 {main abc5 y}               {0 {{} BINARY 0 0 0}}
  23 {main abc5 z}               {0 {{} BINARY 1 1 0}}
  24 {main abc5 rowid}           {1 {no such table column: abc5.rowid}}
  30 {main abc6 rowid}           {0 {TEXT rtrim 0 0 0}}
  31 {main abc6 oid}             {0 {REAL BINARY 0 0 0}}
  32 {main abc6 _rowid_}         {0 {BLOB BINARY 0 0 0}}
}
ifcapable autoinc {
  set tests [concat $tests {
    100 {{} abc4 b}              {0 {INTEGER BINARY 0 1 1}}
    101 {main abc4 rowid}        {0 {INTEGER BINARY 0 1 1}}
  }]
}
ifcapable view {
  set tests [concat $tests {
    200 {{} v1 a}                {1 {no such table column: v1.a}}
    201 {main v1 b}              {1 {no such table column: v1.b}}
    202 {main v1 badname}        {1 {no such table column: v1.badname}}
    203 {main v1 rowid}          {1 {no such table column: v1.rowid}}
  }]
}

foreach {tn params results} $tests {
  set ::DB [sqlite3_connection_pointer db]

  set tstbody [concat sqlite3_table_column_metadata $::DB $params] 
................................................................................

  set ::DB [sqlite3_connection_pointer db]
  set tstbody [concat sqlite3_table_column_metadata $::DB $params] 
  do_test colmeta-$tn.2 {
    list [catch $tstbody msg] [set msg]
  } $results
}

# Calling sqlite3_table_column_metadata with a NULL column name merely
# checks for the existance of the table.
#
do_test colmeta-300 {
  catch {sqlite3_table_column_metadata $::DB main xyzzy} res
} {1}
do_test colmeta-301 {
  catch {sqlite3_table_column_metadata $::DB main abc} res
} {0}


finish_test