'if exist drop index' dose not exist in MYSQL.
So we using user variables.
tableName is table name.
indexName is index name.
columnName is column name.
set @exist := (select count(*) from information_schema.statistics where table_name = 'tableName' and index_name = 'indexName');
set @sqlstmt := if( @exist > 0,
'drop index indexName on tableName',
'create unique index indexName on tableName ( columnName )'
);
PREPARE stmt FROM @sqlstmt;
EXECUTE stmt;
set @sqlstmt := if( @sqlstmt = 'drop index indexName on tableName',
'create unique index catalogItemId on CatalogItemCatalogItemImageModelMeta ( catalogItemId )',
'select success'
);
PREPARE stmt FROM @sqlstmt;
EXECUTE stmt;