return rc;
}


/**************************************************************************
** Beginning of implementation of .fkey_missing_indexes
*/
typedef struct PragmaVtab PragmaVtab;
typedef struct PragmaCursor PragmaCursor;
typedef struct PragmaConfig PragmaConfig;

/*
** Table structure for "pragma" eponymous virtual tables.
*/
struct PragmaVtab {
  sqlite3_vtab base;
  PragmaConfig *pConfig;
  sqlite3 *db;
};

/*
** Cursor structure for "pragma" eponymous virtual tables.
*/
struct PragmaCursor {
  sqlite3_vtab_cursor base;
  sqlite3_stmt *pSelect;
  sqlite3_stmt *pPragma;
  sqlite_int64 iRowid;
};

struct PragmaConfig {
  const char *zModule;
  const char *zSchema;
  const char *zPragma;
};

/* 
** Pragma virtual table module xConnect method.
*/
static int shellPragmaConnect(
  sqlite3 *db,
  void *pAux,
  int argc, const char *const*argv,
  sqlite3_vtab **ppVtab,
  char **pzErr
){
  PragmaConfig *pConfig = (PragmaConfig*)pAux;
  PragmaVtab *pTab = 0;
  int rc;

  rc = sqlite3_declare_vtab(db, pConfig->zSchema);
  if( rc==SQLITE_OK ){
    pTab = (PragmaVtab*)sqlite3_malloc(sizeof(PragmaVtab));
    if( pTab==0 ){
      rc = SQLITE_NOMEM;
    }else{
      memset(pTab, 0, sizeof(PragmaVtab));
      pTab->db = db;
      pTab->pConfig = pConfig;
    }
  }else{
    *pzErr = sqlite3_mprintf("%s", sqlite3_errmsg(db));
  }

  *ppVtab = (sqlite3_vtab*)pTab;
  return rc;
}

/* 
** Pragma virtual table module xDisconnect method.
*/
static int shellPragmaDisconnect(sqlite3_vtab *pVtab){
  PragmaVtab *pTab = (PragmaVtab*)pVtab;
  sqlite3_free(pTab);
  return SQLITE_OK;
}

/* 
** Pragma virtual table module xBestIndex method.
*/
static int shellPragmaBestIndex(sqlite3_vtab *tab, sqlite3_index_info *pIdxInfo){
  return SQLITE_OK;
}

/* 
** Pragma virtual table module xOpen method.
*/
static int shellPragmaOpen(sqlite3_vtab *pVtab, sqlite3_vtab_cursor **ppCursor){
  PragmaCursor *pCsr;

  pCsr = (PragmaCursor*)sqlite3_malloc(sizeof(PragmaCursor));
  if( pCsr==0 ) return SQLITE_NOMEM;
  memset(pCsr, 0, sizeof(PragmaCursor));
  pCsr->base.pVtab = pVtab;

  *ppCursor = (sqlite3_vtab_cursor*)pCsr;
  return SQLITE_OK;
}

/* 
** Pragma virtual table module xClose method.
*/
static int shellPragmaClose(sqlite3_vtab_cursor *cur){
  return SQLITE_OK;
}

/* 
** Pragma virtual table module xNext method.
*/
static int shellPragmaNext(sqlite3_vtab_cursor *pVtabCursor){
  PragmaCursor *pCsr = (PragmaCursor*)pVtabCursor;
  PragmaVtab *pTab = (PragmaVtab*)(pVtabCursor->pVtab);
  sqlite3 *db = pTab->db;
  int rc = SQLITE_OK;

  /* Increment the xRowid value */
  pCsr->iRowid++;

  while( 1 ){
    assert( rc==SQLITE_OK );

    if( pCsr->pPragma ){
      if( SQLITE_ROW!=sqlite3_step(pCsr->pPragma) ){
        rc = sqlite3_finalize(pCsr->pPragma);
        pCsr->pPragma = 0;
      }
    }

    if( rc==SQLITE_OK && pCsr->pPragma==0 ){
      if( SQLITE_ROW!=sqlite3_step(pCsr->pSelect) ){
        rc = sqlite3_finalize(pCsr->pSelect);
        pCsr->pSelect = 0;
      }else{
        const char *zName = (const char*)sqlite3_column_text(pCsr->pSelect, 0);
        char *zSql = sqlite3_mprintf(pTab->pConfig->zPragma, zName);
        if( zSql==0 ){
          rc = SQLITE_NOMEM;
        }else{
          rc = sqlite3_prepare_v2(db, zSql, -1, &pCsr->pPragma, 0);
          if( rc!=SQLITE_OK ){
            pTab->base.zErrMsg = sqlite3_mprintf("%s", sqlite3_errmsg(db));
          }else{
            continue;
          }
        }
      }
    }

    break;
  }

  return rc;
}

/* 
** Pragma virtual table module xFilter method.
*/
static int shellPragmaFilter(
  sqlite3_vtab_cursor *pVtabCursor, 
  int idxNum, const char *idxStr,
  int argc, sqlite3_value **argv
){
  PragmaCursor *pCsr = (PragmaCursor*)pVtabCursor;
  PragmaVtab *pTab = (PragmaVtab*)(pVtabCursor->pVtab);
  int rc;

  sqlite3_finalize(pCsr->pSelect);
  sqlite3_finalize(pCsr->pPragma);
  pCsr->pSelect = 0;
  pCsr->pPragma = 0;
  pCsr->iRowid = 0;

  rc = sqlite3_prepare_v2(pTab->db, 
      "SELECT name FROM sqlite_master WHERE type = 'table' AND rootpage>0",
      -1, &pCsr->pSelect, 0
  );
  if( rc!=SQLITE_OK ){
    pTab->base.zErrMsg = sqlite3_mprintf("%s", sqlite3_errmsg(pTab->db));
    return rc;
  }

  return shellPragmaNext(pVtabCursor);
}

/*
** Pragma virtual table module xEof method.
*/
static int shellPragmaEof(sqlite3_vtab_cursor *pVtabCursor){
  PragmaCursor *pCsr = (PragmaCursor*)pVtabCursor;
  return (pCsr->pSelect==0);
}

/* 
** Pragma virtual table module xColumn method.
*/
static int shellPragmaColumn(
  sqlite3_vtab_cursor *pVtabCursor, 
  sqlite3_context *ctx, 
  int i
){
  PragmaCursor *pCsr = (PragmaCursor*)pVtabCursor;
  switch( i ){
    case 0: /* "database" */
      sqlite3_result_text(ctx, "main", -1, SQLITE_STATIC);
      break;

    case 1: /* "child"/"table" */
      sqlite3_result_value(ctx, sqlite3_column_value(pCsr->pSelect, 0));
      break;

    default:
      sqlite3_result_value(ctx, sqlite3_column_value(pCsr->pPragma, i-2));
      break;
  }

  return SQLITE_OK;
}

/* 
** Pragma virtual table module xRowid method.
*/
static int shellPragmaRowid(sqlite3_vtab_cursor *pVtabCursor, sqlite_int64 *p){
  PragmaCursor *pCsr = (PragmaCursor*)pVtabCursor;
  *p = pCsr->iRowid;
  return SQLITE_OK;
}

/*
** Register the virtual table module with the supplied database handle.
*/
static int shellPragmaRegister(sqlite3 *db){
  static sqlite3_module shellPragmaModule = {
    0,                            /* iVersion */
    shellPragmaConnect,           /* xCreate - create a table */
    shellPragmaConnect,           /* xConnect - connect to an existing table */
    shellPragmaBestIndex,         /* xBestIndex - Determine search strategy */
    shellPragmaDisconnect,        /* xDisconnect - Disconnect from a table */
    shellPragmaDisconnect,        /* xDestroy - Drop a table */
    shellPragmaOpen,              /* xOpen - open a cursor */
    shellPragmaClose,             /* xClose - close a cursor */
    shellPragmaFilter,            /* xFilter - configure scan constraints */
    shellPragmaNext,              /* xNext - advance a cursor */
    shellPragmaEof,               /* xEof */
    shellPragmaColumn,            /* xColumn - read data */
    shellPragmaRowid,             /* xRowid - read data */
    0,                            /* xUpdate - write data */
    0,                            /* xBegin - begin transaction */
    0,                            /* xSync - sync transaction */
    0,                            /* xCommit - commit transaction */
    0,                            /* xRollback - rollback transaction */
    0,                            /* xFindFunction - function overloading */
    0,                            /* xRename - rename the table */
    0,                            /* xSavepoint */
    0,                            /* xRelease */
    0                             /* xRollbackTo */
  };
  int rc = SQLITE_OK;
  int i;

  static PragmaConfig aConfig[] = {
    { "pragma_foreign_key_list",
      "CREATE TABLE x(database, child, "
        "id, seq, parent, child_col, parent_col, on_update, on_delete, match)",
      "PRAGMA foreign_key_list = %Q"
    },
    { "pragma_table_info",
      "CREATE TABLE x(database, tbl, "
        "cid, name, type, not_null, dflt_value, pk)",
      "PRAGMA table_info = %Q"
    }
  };

  for(i=0; rc==SQLITE_OK && i<sizeof(aConfig)/sizeof(aConfig[0]); i++){
    rc = sqlite3_create_module_v2(
        db, aConfig[i].zModule, &shellPragmaModule, (void*)&aConfig[i], 0
    );
  }

  return rc;
}

/*
** The implementation of SQL scalar function fkey_collate_clause(). This

** scalar function is always called with four arguments - the parent
** table name, the parent column name, the child table name and the child
** column name.
**
**   fkey_collate_clause('parent-tab', 'parent-col', 'child-tab', 'child-col')
**
** If either of the named tables or columns do not exist, this function
** returns an empty string. An empty string is also returned if both tables 
** and columns exist but have the same default collation sequence. Or,
** if both exist but the default collation sequences are different, this
................................................................................
** The implementation of dot-command ".fkey_missing_indexes".
*/
static int shellFkeyMissingIndexes(
  ShellState *pState,             /* Current shell tool state */
  char **azArg,                   /* Array of arguments passed to dot command */
  int nArg                        /* Number of entries in azArg[] */
){
  sqlite3 *db = pState->db;
  FILE *out = pState->out;
  int bVerbose = 0;               /* If -verbose is present */
  int bGroupByParent = 0;         /* If -groupbyparent is present */
  int i;
  const char *zIndent = "";



  int rc;
  sqlite3_stmt *pSql = 0;



































  const char *zSql =
    "SELECT "
    "     'EXPLAIN QUERY PLAN SELECT rowid FROM ' || quote(child) || ' WHERE ' "
    "  || group_concat(quote(child) || '.' || quote(child_col) || '=?' || "
    "        fkey_collate_clause(parent, parent_col, child, child_col),' AND ')"

    ", "
    "     'SEARCH TABLE ' || child || ' USING COVERING INDEX*('"
    "  || group_concat('*=?', ' AND ') || ')'"
    ", "
    "     child  || '(' || group_concat(child_col,  ', ') || ')'"
    ", "
    "     parent || '(' || group_concat(COALESCE(parent_col, "
    "       (SELECT name FROM pragma_table_info WHERE tbl=parent AND pk=seq+1)"
    "     )) || ')'"
    ", "
    "     'CREATE INDEX ' || quote(child ||'_'|| group_concat(child_col, '_'))"
    "  || ' ON ' || quote(child) || '('"
    "  || group_concat(quote(child_col) ||"
    "        fkey_collate_clause(parent, parent_col, child, child_col), ', ')"
    "  || ');'"
    ", "
    "     parent "

    "FROM pragma_foreign_key_list GROUP BY child, id "

    "ORDER BY (CASE WHEN ? THEN parent ELSE CHILD END)"
  ;

  for(i=1; i<nArg; i++){
    int n = strlen(azArg[i]);
    if( n>1 && sqlite3_strnicmp("-verbose", azArg[i], n)==0 ){
      bVerbose = 1;
    }
................................................................................
      zIndent = "    ";
    }
    else{
      raw_printf(stderr, "Usage: .fkey_lint ?-verbose? ?-groupbyparent?\n");
      return SQLITE_ERROR;
    }
  }

  /* Register the pragma eponymous virtual tables */
  rc = shellPragmaRegister(db);
  
  /* Register the fkey_collate_clause() SQL function */
  if( rc==SQLITE_OK ){
    rc = sqlite3_create_function(db, "fkey_collate_clause", 4, SQLITE_UTF8,
        0, shellFkeyCollateClause, 0, 0
    );
  }


  if( rc==SQLITE_OK ){
    rc = sqlite3_prepare_v2(db, zSql, -1, &pSql, 0);
  }
  if( rc==SQLITE_OK ){
    sqlite3_bind_int(pSql, 1, bGroupByParent);

  return rc;
}


/**************************************************************************
** Beginning of implementation of .fkey_missing_indexes
*/




/*














































































































































































































































































** The implementation of SQL scalar function fkey_collate_clause(), used
** by the ".fkey_missing_indexes" command. This scalar function is always
** called with four arguments - the parent table name, the parent column name,
** the child table name and the child column name.

**
**   fkey_collate_clause('parent-tab', 'parent-col', 'child-tab', 'child-col')
**
** If either of the named tables or columns do not exist, this function
** returns an empty string. An empty string is also returned if both tables 
** and columns exist but have the same default collation sequence. Or,
** if both exist but the default collation sequences are different, this
................................................................................
** The implementation of dot-command ".fkey_missing_indexes".
*/
static int shellFkeyMissingIndexes(
  ShellState *pState,             /* Current shell tool state */
  char **azArg,                   /* Array of arguments passed to dot command */
  int nArg                        /* Number of entries in azArg[] */
){
  sqlite3 *db = pState->db;       /* Database handle to query "main" db of */
  FILE *out = pState->out;        /* Stream to write non-error output to */
  int bVerbose = 0;               /* If -verbose is present */
  int bGroupByParent = 0;         /* If -groupbyparent is present */
  int i;                          /* To iterate through azArg[] */
  const char *zIndent = "";       /* How much to indent CREATE INDEX by */
  int rc;                         /* Return code */
  sqlite3_stmt *pSql = 0;         /* Compiled version of SQL statement below */



  /*
  ** This SELECT statement returns one row for each foreign key constraint
  ** in the schema of the main database. The column values are:
  **
  ** 0. The text of an SQL statement similar to:
  **
  **      "EXPLAIN QUERY PLAN SELECT rowid FROM child_table WHERE child_key=?"
  **
  **    This is the same SELECT that the foreign keys implementation needs
  **    to run internally on child tables. If there is an index that can
  **    be used to optimize this query, then it can also be used by the FK
  **    implementation to optimize DELETE or UPDATE statements on the parent
  **    table.
  **
  ** 1. A GLOB pattern suitable for sqlite3_strglob(). If the plan output by
  **    the EXPLAIN QUERY PLAN command matches this pattern, then the schema
  **    contains an index that can be used to optimize the query.
  **
  ** 2. Human readable text that describes the child table and columns. e.g.
  **
  **       "child_table(child_key1, child_key2)"
  **
  ** 3. Human readable text that describes the parent table and columns. e.g.
  **
  **       "parent_table(parent_key1, parent_key2)"
  **
  ** 4. A full CREATE INDEX statement for an index that could be used to
  **    optimize DELETE or UPDATE statements on the parent table. e.g.
  **
  **       "CREATE INDEX child_table_child_key ON child_table(child_key)"
  **
  ** 5. The name of the parent table.
  **
  ** These six values are used by the C logic below to generate the report.
  */
  const char *zSql =
  "SELECT "
    "     'EXPLAIN QUERY PLAN SELECT rowid FROM ' || quote(s.name) || ' WHERE '"
    "  || group_concat(quote(s.name) || '.' || quote(f.[from]) || '=?' "

    "  || fkey_collate_clause(f.[table], f.[to], s.name, f.[from]),' AND ')"
    ", "
    "     'SEARCH TABLE ' || s.name || ' USING COVERING INDEX*('"
    "  || group_concat('*=?', ' AND ') || ')'"
    ", "
    "     s.name  || '(' || group_concat(f.[from],  ', ') || ')'"
    ", "
    "     f.[table] || '(' || group_concat(COALESCE(f.[to], "
    "       (SELECT name FROM pragma_table_info(f.[table]) WHERE pk=seq+1)"
    "     )) || ')'"
    ", "
    "     'CREATE INDEX ' || quote(s.name ||'_'|| group_concat(f.[from], '_'))"
    "  || ' ON ' || quote(s.name) || '('"
    "  || group_concat(quote(f.[from]) ||"
    "        fkey_collate_clause(f.[table], f.[to], s.name, f.[from]), ', ')"
    "  || ');'"
    ", "
    "     f.[table] "

    "FROM sqlite_master AS s, pragma_foreign_key_list(s.name) AS f "
    "GROUP BY s.name, f.id "
    "ORDER BY (CASE WHEN ? THEN f.[table] ELSE s.name END)"
  ;

  for(i=1; i<nArg; i++){
    int n = strlen(azArg[i]);
    if( n>1 && sqlite3_strnicmp("-verbose", azArg[i], n)==0 ){
      bVerbose = 1;
    }
................................................................................
      zIndent = "    ";
    }
    else{
      raw_printf(stderr, "Usage: .fkey_lint ?-verbose? ?-groupbyparent?\n");
      return SQLITE_ERROR;
    }
  }
  



  /* Register the fkey_collate_clause() SQL function */

  rc = sqlite3_create_function(db, "fkey_collate_clause", 4, SQLITE_UTF8,
      0, shellFkeyCollateClause, 0, 0
  );



  if( rc==SQLITE_OK ){
    rc = sqlite3_prepare_v2(db, zSql, -1, &pSql, 0);
  }
  if( rc==SQLITE_OK ){
    sqlite3_bind_int(pSql, 1, bGroupByParent);